Avoid reseved identifiers like _SP, etc.

R_SP is not that bad.
Merge pull request #4938 from unknownbrackets/armjit-minor

Avoid reseved identifiers like _SP, etc.
Start untangling our include mess a little.
More include untangling
Delete CPU.cpp/h , cleanup
More include cleanup, hopefully buildfix Symbian
Fix some includes on Windows/etc.
Add ini options to configure the texture cache.
Fix #4922, kill age checks in texcache.
Cleanup differences in DirectX9 texcache code.
Add UI options for new texcache options.
Default off the texture cache options.

They cause noticeable glitches in a bunch of games.  The speed improvement
in some games is very good, but in quite a few it is small.