Add Optimizations for LoongArch.

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

This patch removes the prefetches from cgemm/zgemm which improves the performance similar to sgemm/dgemm did in #3868, this means I'm happy to enable this on any applicable cores.

I also replicated the unrolling the copies from sgemm and dgemm.

In order to enable support for future cores which have similar tunings
(in this case I'm doing this for the Arm(R) Neoverse(TM) V2 core), this generically detects SVE support and enables it. This should better manage the size and complexity of dynamic dispatch rather than just copy pasting the same parameters.

To make `ARMV8SVE` more representive of the common 128-bit SVE case,
I've split it and similar parameters from A64FX which has the wider
512-bit SVE.

Use SVE kernel for SGEMM/DGEMM on Arm(R) Neoverse(TM) V1

Propagate SWITCH_RATIO to DYNAMIC_ARCH builds

This re-spins #3869 with some additional copy unrolling which helps maintain SYRK performance.

After #3868, the SVE kernels represent a pretty good boost.

This re-uses ARMV8SVE as a base and I'm going to incrementally move everything to use ARMV8SVE in additional patches (as well as fix up anything that's not already in ARMV8SVE).

This seems like a good balance of values for reasonably sized matrices. With `SWITCH_RATIO=16` the DGEMM scales better to bigger sizes but the better solution would be some kind of
thread throttling so I've gone with `SWITCH_RATIO=8`.

Previously dynamic builds were either using the default SWITCH_RATIO
or one from the higher level architecture; this patch ensures the
dynamic builds can use this parameter as well.

From testing this yields better results than the default of `2`.

It is really dangerous to fallback to Loongson core on other
MIPS64 processors.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

1. Modify the algorithm to resolve multithreading failures
    2. No memory allocation in sbgemm kernel
    3. Optimize when alpha == 1.0f

implement ncopy tcopy kernel_8x4

SVE zgemm&cgemm (and other BLAS 3 complex)

Fix recent SkylakeX/DYNAMIC_ARCH DGEMM breakage

OpenBLAS: aarch64: Add neoverse-v1/n2 architecture specifics

Add sgemm part for Arm SVE

Fallback for Power kernels

Add dgemm kernel for arm64 SVE