Add Optimizations for LoongArch.

Signed-off-by: Hao Chen <chenhao@loongson.cn>

Signed-off-by: Hao Chen <chenhao@loongson.cn>

Signed-off-by: Hao Chen <chenhao@loongson.cn>

Signed-off-by: Hao Chen <chenhao@loongson.cn>

Signed-off-by: Hao Chen <chenhao@loongson.cn>

These files are exactly the same, so I believe we can reduce these files
down. Other files require a slightly more complex unpicking.

This changes the SVE dot kernel to only predicate when necessary as well
as streamlining the assembly a bit. The benchmarks seem to indicate this
can improve performance by ~33%.

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

Add some refines and optimizations for LoongArch.

for skylake kernels. This is the same method as used in [sd]asum.
_mm_set1_epi64x was commented out for zasum, but has the advantage
of avoiding possible undefined behaviour (using an uninitialized
variable), optimized out by NVHPC and icx. The new code works
fine with those compilers.

For GCC 12.3 the generated code is identical; no matter what method
you use, the compiler optimizes the code into a compile-time
constant, there is no performance benefit using mm_cmpeq_epi8
since the corresponding instruction (VPCMPEQB) isn't actually
generated!

* Temporarily disable the C/ZASUM microkernels for any version of NVHPC