Avoid xinput pad jitter resetting axis state.

Should take care of #5526.
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.
Throw "Disable Alpha Test" into the pile of options to be disabled.
Buildfix.
Merge pull request #6285 from thedax/disable-ui-options

GameSettingsScreen: Disable a bunch of options when software rendering is enabled.
Oops, restore the deleted stencil test option since we haven't decided its fate yet.
Merge pull request #6347 from thedax/restore-stencil-test

Oops, restore the deleted stencil test option since we haven't decided its fate yet.
Qt: Optimisations for ARM desktop/tablet hosts.
Qt: Buildfix USING_GLES2 and not MOBILE_DEVICE
glBindFragDataLocation is not needed. Thanks HdkR.
Support fixed/fixed blending without a blit.
Convert blending to doubling in more cases.

We're not doubling the alpha, so all these cases are safe regardless of
the alpha value.
Support more src alpha doubling modes.

These prevent the need for more blits.
Reorganize alphablend state mapping logic.
Use shader blend for min/max when unsupported.
Merge pull request #6342 from unknownbrackets/xinput-fix

Avoid xinput pad jitter resetting axis state
Merge pull request #6350 from unknownbrackets/gpu-blend

Avoid blitting for a bunch of gpu blending modes
Disable vsync when exiting the game.

Not sure why, but with some drivers not doing this makes the process burn
cpu usage when back in the menu.  Fixes #6351.