Bring back some ifdefs
Update Symbian to GCC 4.8.3
Disable precision qualifiers on desktop GL
Merge pull request #6287 from hrydgard/desktop-shader-precision

Disable precision qualifiers on desktop GL
Revert "Remove option" (disable alpha test)

Fixes issue #6286.

This reverts commit d2ce635bbfbf2a68517ed7eac10b3923d0f3c3c8.