Jit: lwl/lwr/swl/swr, shift var

Not really a huge improvement in performance at all, but speeds up debug a bit.

Also a tiny fix in case code ever jumps into a delay slot (don't try to compile the emuhack.)  I've never actually seen a game do this, though.

By the way, I noticed numInstructions doesn't account for delay slots, but I'm not sure if this is intentional.

-[Unknown]