Bug 941296 - h.264 platform decoder for OS X. r=cpearce

Implement an h.264 decoder using Apple's VideoToolbox framework.
Based on gstreamer's vtdec because there's very little documentation
for this API beyond the framework's header file.

Reuse the MOZ_APPLEMEDIA define from the mp3 decoder.

AAC decoding is stubbed to use the BlankDecoderModule's 440A tone.

Provide a stub header for the VideoToolbox framework and load
it dynamically at run time so we can build and run on versions
prior to MacOS X 10.8 where it's not available.

Dynamically load the CoreMedia framework as well, but build
against its headers since it's available on MacOS X 10.7 or
later, which is our minimum build version.
Bug 941296 - Add a missing close brace. r=cpearce

Accidentally clobbered this when adding the APPLEMEDIA #ifdef.
Fixes build against ffmpeg, etc.
Bug 941296 - Fix warnings from debug-only code. r=cpearce

These reported as unused variable warnings in non-debug builds.
Bug 941296 - AAC platform decoder for OS X. r=edwin,cpearce

Implement an AAC decoder based on the AudioToolbox wrapper
in AppleMP3Decoder.
Bug 941296 - Fix type conversion errors on 32-bit MacOS. r=cpearce

UInt32 is an unsigned long on i686 while uint32_t is an unsigned int.
The compiler can't covert from a pointer to one to the pointer to
the other, so just use the MacOS type.

There's no problem on 64-bit.
Bug 941296 - Enable FMP4 when APPLEMEDIA is enabled. r=cpearce,ted

This requires moving the MOZ_APPLEMEDIA define. I put it in
alphabetical order with the other platform decoder checks.

Also removes the --disable-apple-media configure switch.
We don't have proper testing for these options, so it's
better not to offer the choice.