Implementing SVE in `[SD]AXPY` Kernels for `A64FX` and `Graviton3E`

Optimize the gemv_t_vector.c  kernel  for  RISCV64_ZVL256B target

Increase L2 defaults for RISCV X280 / ZVL256B and ARM SVE targets in CMake cross-compilation

fix: broken cblas installation when using makefile based builds

Add and use vectorized packing in ZVL128B and ZVL256B for RISCV

Move the value assignment of vector x in gemv_n_sve.c to the outermos…

Optimize SBGEMM / BGEMM for NEOVERSEV1 further

Fix cblas.h missing from target directory if NO_CBLAS is defined but has
a value that indicates you do want cblas built and installed.

1.Verify correctness using BLAS-Tester
    2.Using the built-in benchmark to verify performance, the performance of float and doule type improved by about 60% and about 40% respectively.The test command is:
     export OMP_NUM_THREADS=1;numactl -C 10 -l ./sgemv.goto 3000 4000 100
     export OMP_NUM_THREADS=1;numactl -C 10 -l ./dgemv.goto 3000 4000 100

This changes the kernels to pack full SVE vectors and reduces the
overall complexity of the inner GEMM loop.

* Update to 20.1.8

* fix PATH to avoid the obsolete LLVM19 that appeared in the preinstalled msvc folder hierarchy

On some x86 configurations, this fails with (see error below)

It seems that there are many x86 configurations supported by OpenBLAS,
specific for various CPU family names.
But, if (on some x86 builds) this isn't met, then some parameters become
undefined.

Link:
  https://github.com/openwrt/packages/pull/27179#issuecomment-3163947279

```
In file included from ../../common.h:586,
                 from gemm3m.c:40:
gemm3m_level3.c: In function 'cgemm3m_nn':
../../common_param.h:1435:33: error: 'CGEMM3M_DEFAULT_R' undeclared (first use in this function); did you mean 'CGEMM_DEFAULT_R'?
 1435 | #define CGEMM3M_R               CGEMM3M_DEFAULT_R
      |                                 ^~~~~~~~~~~~~~~~~
../../common_param.h:1671:25: note: in expansion of macro 'CGEMM3M_R'
 1671 | #define GEMM3M_R        CGEMM3M_R
      |                         ^~~~~~~~~
gemm3m_level3.c:306:37: note: in expansion of macro 'GEMM3M_R'
  306 |   for(js = n_from; js < n_to; js += GEMM3M_R){
      |                                     ^~~~~~~~
../../common_param.h:1435:33: note: each undeclared identifier is reported only once for each function it appears in
 1435 | #define CGEMM3M_R               CGEMM3M_DEFAULT_R
      |                                 ^~~~~~~~~~~~~~~~~
../../common_param.h:1671:25: note: in expansion of macro 'CGEMM3M_R'
 1671 | #define GEMM3M_R        CGEMM3M_R
      |                         ^~~~~~~~~
gemm3m_level3.c:306:37: note: in expansion of macro 'GEMM3M_R'
  306 |   for(js = n_from; js < n_to; js += GEMM3M_R){
      |                                     ^~~~~~~~
../../common_param.h:1434:33: error: 'CGEMM3M_DEFAULT_Q' undeclared (first use in this function); did you mean 'CGEMM_DEFAULT_Q'?
 1434 | #define CGEMM3M_Q               CGEMM3M_DEFAULT_Q
      |                                 ^~~~~~~~~~~~~~~~~
../../common_param.h:1661:25: note: in expansion of macro 'CGEMM3M_Q'
 1661 | #define GEMM3M_Q        CGEMM3M_Q
      |                         ^~~~~~~~~
gemm3m_level3.c:313:20: note: in expansion of macro 'GEMM3M_Q'
  313 |       if (min_l >= GEMM3M_Q * 2) {
      |                    ^~~~~~~~
i486-openwrt-linux-musl-gcc -Os -pipe -march=pentium-mmx -fno-caller-saves -fno-plt -fhonour-copts -ffile-prefix-map=/builder/build_dir/target-i386_pentium-mmx_musl/OpenBLAS-0.3.30=OpenBLAS-0.3.30 -Wformat -Werror=format-security -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro  -I/builder/staging_dir/toolchain-i386_pentium-mmx_gcc-14.3.0_musl/usr/include -I/builder/staging_dir/toolchain-i386_pentium-mmx_gcc-14.3.0_musl/include -I/builder/staging_dir/toolchain-i386_pentium-mmx_gcc-14.3.0_musl/include/fortify   -DMAX_STACK_ALLOC=2048 -DEXPRECISION -m128bit-long-double -Wall -m32 -DF_INTERFACE_GFORT -fPIC -DC_LAPACK -DNO_LAPACK -DNO_LAPACKE -DNO_AVX -DNO_AVX512 -DSMP_SERVER -DNO_WARMUP -DMAX_CPU_NUMBER=2 -DMAX_PARALLEL_NUMBER=1 -DBUILD_SINGLE=1 -DBUILD_DOUBLE=1 -DBUILD_COMPLEX=1 -DBUILD_COMPLEX16=1 -DVERSION=\"0.3.30\" -UASMNAME -UASMFNAME -UNAME -UCNAME -UCHAR_NAME -UCHAR_CNAME -DASMNAME= -DASMFNAME=_ -DNAME=_ -DCNAME= -DCHAR_NAME=\"_\" -DCHAR_CNAME=\"\" -DNO_AFFINITY -I.  -DMAX_STACK_ALLOC=2048 -DEXPRECISION -m128bit-long-double -Wall -m32 -DF_INTERFACE_GFORT -fPIC -DC_LAPACK -DNO_LAPACK -DNO_LAPACKE -DNO_AVX -DNO_AVX512 -DSMP_SERVER -DNO_WARMUP -DMAX_CPU_NUMBER=2 -DMAX_PARALLEL_NUMBER=1 -DBUILD_SINGLE=1 -DBUILD_DOUBLE=1 -DBUILD_COMPLEX=1 -DBUILD_COMPLEX16=1 -DVERSION=\"0.3.30\" -UASMNAME -UASMFNAME -UNAME -UCNAME -UCHAR_NAME -UCHAR_CNAME -DASMNAME=cgemm3m_cn -DASMFNAME=cgemm3m_cn_ -DNAME=cgemm3m_cn_ -DCNAME=cgemm3m_cn -DCHAR_NAME=\"cgemm3m_cn_\" -DCHAR_CNAME=\"cgemm3m_cn\" -DNO_AFFINITY -I../.. -UDOUBLE  -DCOMPLEX  -c -UDOUBLE -DCOMPLEX -DCN gemm3m.c -o cgemm3m_cn.o
../../common_param.h:1433:33: error: 'CGEMM3M_DEFAULT_P' undeclared (first use in this function); did you mean 'CGEMM_DEFAULT_P'?
 1433 | #define CGEMM3M_P               CGEMM3M_DEFAULT_P
      |                                 ^~~~~~~~~~~~~~~~~
../../common_param.h:1651:25: note: in expansion of macro 'CGEMM3M_P'
 1651 | #define GEMM3M_P        CGEMM3M_P
      |                         ^~~~~~~~~
gemm3m_level3.c:325:20: note: in expansion of macro 'GEMM3M_P'
  325 |       if (min_i >= GEMM3M_P * 2) {
      |                    ^~~~~~~~
../../common_param.h:1436:33: error: 'CGEMM3M_DEFAULT_UNROLL_M' undeclared (first use in this function); did you mean 'CGEMM3M_DEFAULT_UNROLL_N'?
 1436 | #define CGEMM3M_UNROLL_M        CGEMM3M_DEFAULT_UNROLL_M
      |                                 ^~~~~~~~~~~~~~~~~~~~~~~~
../../common_param.h:1580:25: note: in expansion of macro 'CGEMM3M_UNROLL_M'
 1580 | #define GEMM3M_UNROLL_M CGEMM3M_UNROLL_M
      |                         ^~~~~~~~~~~~~~~~
gemm3m_level3.c:329:33: note: in expansion of macro 'GEMM3M_UNROLL_M'
  329 |           min_i = ((min_i / 2 + GEMM3M_UNROLL_M - 1)/GEMM3M_UNROLL_M) * GEMM3M_UNROLL_M;
      |                                 ^~~~~~~~~~~~~~~
make[4]: *** [Makefile:1865: cgemm3m_nn.o] Error 1
make[4]: *** Waiting for unfinished jobs....
In file included from ../../common.h:586,
                 from gemm3m.c:40:
gemm3m_level3.c: In function 'cgemm3m_cn':
../../common_param.h:1435:33: error: 'CGEMM3M_DEFAULT_R' undeclared (first use in this function); did you mean 'CGEMM_DEFAULT_R'?
 1435 | #define CGEMM3M_R               CGEMM3M_DEFAULT_R
      |                                 ^~~~~~~~~~~~~~~~~
../../common_param.h:1671:25: note: in expansion of macro 'CGEMM3M_R'
 1671 | #define GEMM3M_R        CGEMM3M_R
      |                         ^~~~~~~~~
gemm3m_level3.c:306:37: note: in expansion of macro 'GEMM3M_R'
  306 |   for(js = n_from; js < n_to; js += GEMM3M_R){
      |                                     ^~~~~~~~
../../common_param.h:1435:33: note: each undeclared identifier is reported only once for each function it appears in
 1435 | #define CGEMM3M_R               CGEMM3M_DEFAULT_R
      |                                 ^~~~~~~~~~~~~~~~~
../../common_param.h:1671:25: note: in expansion of macro 'CGEMM3M_R'
 1671 | #define GEMM3M_R        CGEMM3M_R
      |                         ^~~~~~~~~
gemm3m_level3.c:306:37: note: in expansion of macro 'GEMM3M_R'
  306 |   for(js = n_from; js < n_to; js += GEMM3M_R){
      |                                     ^~~~~~~~
../../common_param.h:1434:33: error: 'CGEMM3M_DEFAULT_Q' undeclared (first use in this function); did you mean 'CGEMM_DEFAULT_Q'?
 1434 | #define CGEMM3M_Q               CGEMM3M_DEFAULT_Q
      |                                 ^~~~~~~~~~~~~~~~~
../../common_param.h:1661:25: note: in expansion of macro 'CGEMM3M_Q'
 1661 | #define GEMM3M_Q        CGEMM3M_Q
      |                         ^~~~~~~~~
gemm3m_level3.c:313:20: note: in expansion of macro 'GEMM3M_Q'
  313 |       if (min_l >= GEMM3M_Q * 2) {
      |                    ^~~~~~~~
```

Fix compilation of the NeoverseN2 SBGEMM kernel

Multi-thread Performance Improvement of GEMM on NeoverseV1 with DIVIDE_RATE=1

Adjust multithreading threshold in S/DGER and add an intermediate step

Work around gcc15.1 on POWER misoptimizing DGEMV at -O3

Fix bad vector zero initializer and other compiler warnings for RISC-V.

Fix building of bgemm tests on GEMM3M-capable (x86) targets

ARM64: Enable bfloat16 kernels by default

Introduce a (crude) threshold to multithreading in STRMV/DTRMV

Add NEOVERSEV2 target support

Include float-bfloat conversion functions in ONLY_CBLAS builds as well

Add optimized BGEMM for NEOVERSEN2 target

Use OpenBLAS_ROOT_DIR in OpenBLASConfig.cmake generation only if set

Update ?GEMM-to-?GEMV forwarding settings for CMake

Did a quick run around to make `TARGET=NEVOERSEV2` build successfully.

Fixes #5385