Fix and re-enable vdot again on x86

This does a couple other things too:
 * turns on fast/sse2 on debug, release x64, and release x64.  Better if they match.
 * fixes a transpose bug in the disasm (be631de), correct me if I'm wrong.
 * Adds a flag `OUT_EAT_PREFIX` to MIPSTables, and some values based on testing.

Unfortunately, a lot of the ops I'm seeing are at the start of a branch, so this still doesn't help perf much.  Anyway, I did find a small and surely uncommon bug in vdot, at least.

-[Unknown]