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.
GameSettingsScreen: Disable a bunch of options when software rendering is enabled.
They don't do anything when software rendering is enabled, so there's bound to be confusion caused by these options continuing to be enabled.

Conflicts:
	UI/GameSettingsScreen.cpp
Disable more stuff, and use cached booleans instead.

Conflicts:
	UI/GameSettingsScreen.cpp
Do it for post-processing and resolution too, to be consistent.