Add notaz's gles2rice neon optimizations

Backported neon optimizations from https://github.com/ptitSeb/mupen64plus-pandora/commits/master

commits 0764a4751fb12ff200c29943700ee45b3722f102 to 6c7533683f3b805c127b433aa5a7c8b1ce0c775b

On my device it has no actual speed gains but improves accuracy in shown graphics.

Tested on armv7 machine, should be tested on other platrform targets.