Avoid alpha test when vertexFullAlpha && textureFullAlpha

This reduces the amount of alpha tested draws calls from 98% to about 20% in Grand Theft Auto - LCS. 

Won't have as drastic results in all games but will help some.

This is important because alpha testing is terribly expensive on mobile chips, especially PowerVR and Tegra 3 but also others. PSP games just use it willy nilly without caring because on PSP it's free, so we need to rule out when it will have an effect and disable it as often as possible without breaking graphics.

This is not yet taking into account that the lighting equation could possibly change alpha. All games I've tested still draw fine though, but this will also need to be addressed.