Update TestExpectations after enabling web audio.
Update PlatformHaiku cmakefile to better match the EFL one

* No functional changes, just for easier comparison with other
platforms.
WIP implementation of audio support.

* The ffmpeg add-on is reporting only supported encoding types, and we
need decoding ones
* Moreover, the Media Kit hybrid support is broken, so trying to use
BMediaFile and BMediaTrack will lead to loading the gcc2 ffmpeg plug-in
in our gcc4 app (which fails, of course).

The point of this is to make the testsuite fail more reliably. Some
audio tests will hit an assert, rather than crashing because of a null
pointer, so we have an error message with the file and line where the
problem happens.