This patch introduces new optimized version of SHGEMM kernel
using power10 Matrix-Multiply Assist (MMA) feature introduced in
POWER ISA v3.1. This patch makes use of new POWER10 compute instructions
for matrix multiplication operation.

Tested on simulator and there are no new test failures.

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.

at least one of these changes apparently is an oversimplification, leading to TRMM breakage on some platforms as observed in #1563

* dead increments in driver/level2

* dead increments in kernel/generic

* part dead increments in kernel/x86_64

...and does not appear to be needed even when it stays within the bounds of the array

Also, add a generic ztrmm 4x4 kernel

The Ximatcopy functions create a copy of the input matrix
although they seem to work inplace. The new routines
XIMATCOPY_K_YY perform the operations inplace if the leading
dimension does not change.

make TARGET=GENERIC

?gemm3m is unimplemented on generic target.

Optimizations for APM's xgene-1 (aarch64).

1) general system updates to support armv8 better.  Make all did not work, one needed to supply TARGET=ARMV8.
2) sgem 4x4 kernel in assembler using SIMD, and configuration changes to use it.
3) strmm 4x4 kernel in C.  Since the sgem kernel does 4x4, the trmm kernel must also do 4xN.

Added Dave Nuechterlein to the contributors list.

Signed-off-by: Timothy Gu <timothygu99@gmail.com>

So far, this kernel doesn't deal with edge.

AUGEM: Automatically Generate High Performance Dense Linear Algebra
Kernels on x86 CPUs.
Qian Wang, Xianyi Zhang, Yunquan Zhang, and Qing Yi. In the
International Conference for High Performance Computing, Networking,
Storage and Analysis (SC'13). Denver, CO. Nov, 2013.