Fix all the current issues with the AArch64 register cache.
Fixes all the current issues I've been experiencing.
Scaled back the register cache idea for now so I can actually work on some real instructions.

Tested this work with unit tests so I know it works.
Unit tests are pretty great things.
JIT: optimize andi(s)_rc

We usually don't need to do a sign-extend for the resulting flags.
JIT: save an instruction in psq_l
Merge pull request #1065 from Sonicadvance1/AArch64-fix-regcache

Fix all the current issues with the AArch64 register cache.
Merge pull request #1077 from FioraAeterna/integeropts2

Two small JIT optimizations
Revert "Two small JIT optimizations"
Merge pull request #1088 from FioraAeterna/revert-1077-integeropts2

Revert "Two small JIT optimizations"