Adjust SkylakeX GEMM3M parameters, add an AVX512 STRMM kernel and fix performance bugs in AVX2 s/c/z GEMM

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

[WIP] Add support for Ampere EMAG8180 ARMV8 cpu

the fallbacks from Makefile.L1 assume a combined source for absolute value and non-absolute (with ifdef USE_ABS) but here we have separate implementations

the fallbacks from Makefile.L1 assume a combined source for absolute value and non-absolute (with ifdef USE_ABS) but here we have separate implementations

to fix utest failure in new ismin test -  Makefile.L1 defaults look wrong

The was a typo in iamax_sse.S where one of the comparison
was cmpeqps instead of cmpeqss. That misdetected index
for sequences where the minimum value was 0.

The leaq instructions in dscal_kernel_inc_8 modify x and x1 so they
must be declared as input/output constraints, otherwise the compiler
may assume the corresponding registers are not modified.

Improve paralleled SGEMM performance on SKYLAKEX CPUs

BTW some kernels were adjusted to improve performance

Fix SKYLAKEX STRMM issues

Optimize AVX2 SGEMM & STRMM