Improve the performance of sbgemm_tcopy on neoversen2

Remove prefetches from SVE kernels

This is a precursor to enabling the SVE kernels for Arm(R) Neoverse(TM)
V1 which has 256-bit SVE. Testing revealed that the SVE kernel was
actually worse in some cases than the existing kernel which seemed odd -
removing these prefetches the underlying architecture seems to do a better job
😸

Unlike [dcz]scal, sscal still used the original GotoBLAS SSE code from scal_sse.S.
This code follows dscal as closely as possible, except for the inc_x > 1 code
for which a plain C loop is used much like the one in cscal.c, instead of an
adaptation of the SSE2 asm code of dscal.c (I tried but the performance wasn't
better than the plain C loop).

dscal: use ymm registers in Haswell microkernel

Using 256-bit registers in dscal makes this microkernel consistent with
cscal and zscal, and generally doubles performance if the vector fits in
L1 cache.

This adds an SVE implementation to sdot/ddot when available, falling back to the previous Advanced SIMD kernel where there's no SVE implementation for the kernel.

All the targets were essentially treating `dot_thunderx2t99.c` as the Advanced SIMD implementation so I've renamed it to better fit with the feature detection.

The existing kernel was issuing extra instructions to organise the arguments into the same registers they would usually be in and similarly to put the result into the appropriate register.

This has an impact on smaller sized dots and seemed like a quick fix

These are as similar to dscal_microk_skylakex-2.c as possible
for consistency.

Note that before this change SKYLAKEX+ uses generic C functions for
cscal/zscal via commit 2271c350 from #2610 (which is masked by
commit 086d87a30). However now #3799 disables FMAs (in turn enabled
by `-march=skylake-avx512`) in the plain C code which fixes excessive
LAPACK test failures more nicely.

x86_64: prevent GCC and Clang from generating FMAs in cscal/zscal.

If e.g. -march=haswell is set in CFLAGS, GCC generates FMAs by default, which
is inconsistent with the microkernels, none of which use FMAs. These
inconsistencies cause a few failures in the LAPACK testcases, where
eigenvalue results with/without eigenvectors are compared.

Moreover using FMAs for multiplication of complex numbers can give surprising
results, see 22aa81f for more information.

This uses the same syntax as used in 22aa81f for zarch (s390x).

1. Use UZP instructions but not gather load and scatter store instructions to get lower latency.
    2. Padding k to a power of 4.

Add pragma to disable the gcc tree-optimizer for some x86_64 S and Z kernels with gcc12 on OSX or Windows

Make it work on general MIPS64 processors

It is really dangerous to fallback to Loongson core on other
MIPS64 processors.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

It will be defined by preprocessor argument.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

SPARC: fix DNRM2 returning INF instead of zero due to intermediate overflow

POWER: Fix complex dot function failures

POWER10: dgemv builtin rename

There are some test failures in complex dot functions when compiling with gcc12.
The machine constraints used now do not update all the four elements in the
expected result array. Fixing this with a reduced level of optimization.
This is not changing any performance numbers but will be converted to C code in future.

Add check to use correct builtin name for older versions
of gcc10 compilers.