armjit: Speed up imm addresses in slowmem mode.
armjit: improve mem speed without fastmem.
armjit: No, LDR/STR do not update flags.

Oops, had some other bug and thought this was the issue.
armjit: Refactor slowmem path for reusing it.
armjit: improve slowmem, fix vram check.

Darn, copy/paste error.