Minor GPU code cleanups
Add a conservative check that prevents alpha testing in a few cases.

This will become really powerful if we add some code to the vertex decoder
to check for non-full alpha in the vertices, and set gstate_c.vertexFullAlpha if none
is found (probably want to do the reverse, set it to true and clear if any non-255 alpha is found).

Alpha testing is a performance killer on many mobile GPUs so big efforts to
avoid it can be worth it.
Use vldmia not vld1 for QuickTexHashNEON().

It turns out this is ~20% slower usually, so aligned is not worth the
pipeline hit.
Minor improvements to QuickTexHashNEON().

Cuts a VFP switch, oops.
Don't use aligned loads in non-inlined funcs.

I'm wanting things to stay in registers, but that's not realistic for
arguments.  Force inline the others.  May help #5699.
Merge remote-tracking branch 'origin/master' into master_0.9.8
fix savestate for mediaengin