Prevent unknown getpointer in sceKernelMemset

Fix #7064
Add some jit benchmarking code.
Cut down on test overhead a good bit.
x86jit: Implement other forms of vx2i.

Gains 3.2% performance in Grand Knights History.
Merge pull request #7065 from sum2012/memset

Prevent unknown getpointer in sceKernelMemset
Merge pull request #7067 from unknownbrackets/jit-bench

Add some jit benchmarking code
Merge pull request #7068 from unknownbrackets/jit-minor

x86jit: Implement other forms of vx2i
Oops, these should be signed.
Fix Windows build without dxsdk (#7070.)
x86jit: Implement vfad and vavg.
x86jit: Implement vi2x instructions.

Also, my opcodes were wrong in the test (shifted the pair bit the wrong
way, oops.)

AFAICT, there's no reason PSRAD/etc. were not encoding REX...
x86jit: Micro optimize vi2x a bit with ssse3/sse4.

Both are small wins.
x86jit: Avoid some regcache pollution.
x86jit: Simplify vavg a bit.
x86jit: Oops, can't have an imm here.
x86jit: Micro optimize vi2f a little bit.

This didn't help overall perf much but micro benchmarks are better.
Merge pull request #7071 from unknownbrackets/jit-minor

x86jit: Implement vfad/vavg and vi2x
x86jit: Micro optimize cvt.s.w a bit.

This implementation is about 5x faster for micro benchmarks.  Little
impact to overall perf in games I tested, though.
Merge pull request #7072 from unknownbrackets/jit-minor

x86jit: Micro optimize cvt.s.w a bit
vertexjit: Optimize weights on x64 (not 32-bit.)

A few percent in Gods Eater Burst and Kingdom Hearts.