instead of current "make output file of size less than ss".
Also use it to make MP3 tests more readable (using -fs xxx where xxx is
the requested output size, not something slightly lower).
Originally committed as revision 24884 to svn://svn.ffmpeg.org/ffmpeg/trunk
This moves some groups of tests for single codecs to separate files,
and adds shorthands for running all tests in a group.
Originally committed as revision 24697 to svn://svn.ffmpeg.org/ffmpeg/trunk
