vertexjit: Implement Morph pos/nrm variants on x86

Not doing color for two reasons: it seems complicated, and I didn't easily find any games that use it.

Anyway, LittleBigPlanet for example uses this.  Naturally, x86 doesn't need this so much but seems like ARM could do roughly the same...

S8/S16 generate a bit of code for large morphcounts.  I considered making it a real loop (there's enough regs), but not sure if it really matters that much.

Didn't end up impacting perf much in LittleBigPlanet or etc., didn't entirely expect it to but thought it might.  Oh well, doesn't hurt.

-[Unknown]