texcache: SSE optimized version of the most common case of Unswizzle

(didn't put this in fast_math because it's pretty specific to PSP)
Transform: Compute the "DCID" (draw call ID) incrementally instead of an extra pass.
vertexjit: Support morph pos/norm on ARM as well.
vertexjit: support 8888 morph on ARM.
vertexjit: Attempt 16-bit color morphs on ARM.
vertexjit: Save S16-S31 registers in ARM.
vertexjit: Implement NEON color morphs on ARM.
vertexjit: Improve NEON align on color morph ARM.
vertexjit: Combine a few loads and stores on ARM.
Log if any games are actually using s8 through.

Not sure about z sign.
vertexjit: Avoid switching to VFP from NEON.
vertexjit: Try to avoid a few more VFP switches.
vertexjit: Turn on NEON color morphs on ARM.
vertexjit: Don't use NEON morphing when skinning.

Registers overlap.
Add a NEON VMOV imm encoding to the emitter.
Support other constant VMOVs on NEON.

Float is especially useful.
vertexjit: Avoid skinning VFP switching.
Implement NEON register VMOVs.
vertexjit: Avoid the VFP more in some weight funcs.
vertexjit: Use NEON for prescale as well.

Just to keep the VFP out of the picture.