Make NO_AVX512 option override the AVX512 compile test in CMAKE builds as well

Work around ARMV8 build-time cpu detection problems on non-Linux systems

Enable new build target platform -- COOPERLAKE. This target platform
supports all the SKYLAKEX supported ISAs + avx512bf16. So all the
SKYLAKEX specific kernels/drivers and related code are now extended
to be also active on COOPERLAKE. Besides, new BF16 related kernels
are active under this target.

Adjust A53 SGEMM parameters to reflect recent switch to 8x8 kernel

powerpc: Add support for future processor

This is the initial patch to support build infrastructure
for POWER10 architecture.

Add CMAKE support for MAX_STACK_ALLOC setting

* make building the bfloat16 BLAS functions conditional on BUILD_HALF

* pass the BUILD_HALF option to gensymbol

* Pass BUILD_HALF as a compiler define for dynamic_arch builds

Supports ifeq and ifneq, but requires both to have an else branch

This patch adds support for bfloat16 data type matrix multiplication kernel.
For architectures that don't support bfloat16, it is defined as unsigned short
(2 bytes).  Default unroll sizes can be changed as per architecture as done for
SGEMM and for now 8 and 4 are used for M and N.  Size of ncopy/tcopy can be
changed as per architecture requirement and for now, size 2 is used.

Added shgemm in kernel/power/KERNEL.POWER9 and tested in powerpc64le and
powerpc64.  For reference, added a small test compare_sgemm_shgemm.c to compare
sgemm and shgemm output.

This patch does not cover OpenBLAS test, benchmark and lapack tests for shgemm.
Complex type implementation can be discussed and added once this is approved.

as shown in Reference-LAPACK issue 401 (their PR 403)

Use proper extension on the avx512 testcase filename

The need to call it .tmp existed only when it was generated by a tmpfile call, and the "-x c" option to tell the compiler it is actually a C source is not universally supported (this broke the test with clang-cl at least)

tentative fix for #2472

The implementation is a hybird of the ARMV8 one with some of the
improved TX2 rountines along with specifying -march=v8.2-a