JIT64: optimize CA calculations

**JIT64: optimize CA calculations**

Omit carry calculations that get overwritten later in the block before they're used. Very common in the case of srawix and friends.

I previously had a patch to do PS1 optimizations too here but I dropped it for now because it was becoming rather scary and messy (and still broken).

**Please only review the last patch in this PR; the others are just patches that it depends on (the FPRF branch and integeropts branch).**
Maybe fix {"fsqrtsx" alignment here too, even though it's not your fault. I'm not sure what the policy is relating to theses not implemented lines, if the different alignment is meant to draw attention to these lines or what. If they are supposed to be like that please disregard.