CGEMM & ZGEMM using C code, Power only, P10 only.

1. Remove the FADD insn from the GEMV Transpose code.
  2. Remove the FADD insn from GEMM and ZGEMM code.
  3. Reorder the compution of the Imaginary part in ZGEMM code.

This patch fixes following lapack failures with clang compiler on POWER.
zed.out: ZVX:   18 out of  5190 tests failed to pass the threshold
zgd.out: ZGV drivers:     25 out of   1092 tests failed to pass the threshold
zgd.out: ZGV drivers:      6 out of   1092 tests failed to pass the threshold

Fix regression SAXPY when compiler with OpenXL compiler.

SAXPY built with OpenXL regresses when compared to SAXPY
built with gcc. OpenXL compiler doesn't know that the
SAXPY inner kernel assembly is a 64 element loop and
to it the remainder loop is the main loop. It vectorizes
and interleaves the remainder to be a 48 elements per
iteration loop. With a max of 63 iterations, a 48 element
loop is mostly not going to get executed, so the 1 element
scalar loop that is the remainder after that is probably
mostly what gets executed.

This can be fixed by adding a pragma, loop interleave_count(2)
which will result in 8 element loop.

Signed-off-by: Amrita H S <amritahs@linux.vnet.ibm.com>

This reverts commit accea1555159d0928a6aa2db740c042c7e8f0dd3, reversing
changes made to b925353006.

Cgemm zgemm c code

Fixes: https://github.com/OpenMathLib/OpenBLAS/issues/4366

POWER10 optimizations are disabled when using default AIX assembler.
As we have fixed many issues recently, enabling optimization path
for default assembler.

As cgemm and zgemm kernels are not optimized for big endian falling
back to POWER8 versions.  Tested on AIX using gcc and Open XL C.

Modernize obsolete inline order

__builtin_vsx_assemble_pair was only in GCC 10-11.2 and was replaced by
__builtin_vsx_build_pair thereafter.

This patch removes the warning messages related to unused variables in
sbgemm_kernel_power10.c.

Signed-off-by: Manjul Mohan <manjul@linux.vnet.ibm.com>

POWER: Fix complex dot function failures

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.

This patch fixes an issue when OpenBLAS is compiled for TARGET=POWER10
and the flag USE_THREAD is set to 0.

The function `num_cpu_avail` is only available when USE_THREAD=1,
so SMP is defined.

POWER10: Fix ZGEMM testcase failures

This patch fixes storing and restoring non volatile registers
in zgemm POWER10 kernel.

This patch makes use of compiler builtins and matches with assembly
performance. Tested with clang14 and gcc12.

This patch changes 32 bytes stores to two 16 bytes stores
to fix a recent degradation due to 32 bytes stores.