Buildfix: Symbian, CMake-based compiles.
Update ffmpeg (added missing headers for android)
Android buildfix
Windows: Use prebuilt FFMPEG for 32-bit builds.
Mac build fix
Keep track of whether a texture has alpha.

This way we know what sorts of blending we even have to do.  Commonly,
textures don't have any real alpha.

Not yet used for anything.
Ignore texfunc RGBA when texture is full alpha.

This allows us to skip some work in the fragment shader.
Detect clears, replace with glClear(). Needs more testing, disabled for now.
Clean up some comments.
Merge pull request #1727 from unknownbrackets/perf

Keep track of whether textures have alpha values or not
Make some logging VERBOSE
Show an error message instead of crashing on demos we don't have keys for
Only add stream data when it need more atrac data.

Tested with Djmax Portable.
Merge pull request #1731 from oioitff/atrac-fix

Only add stream data when it need more atrac data.
Custom Fps Limiter

First time contributing. Set FPS limit on second page of graphics
settings. Press Tab key or on 360 controller, press left stick to toggle
between 3 states.
Use CoreTiming::AdvanceQuick();
Only double the color with color doubling.

Not the alpha.
Merge pull request #1741 from unknownbrackets/gpu-minor

Only double the color with color doubling
Merge pull request #1740 from raven02/patch-5

Complete fix overbright issue in FF Type-0
Implement DXT3 alpha.