Force 5 byte jumps to avoid jump target issues (vertex jit, x86)

Some with 16-bit colors were too far.  Should've realized, my bad.

By the way, I played with drawsUntilNextFullHash and numVerts a bit.  Even much more conservative values were still way faster than vertex cache off.  But I think the situation with that one game that @raven02 was trying is much more interesting.

-[Unknown]