Merge remote-tracking branch 'qatar/master'

* qatar/master:
  fate: Fix fate-ac3-fixed-encode for pre-ssse3 x86 machines
  http: Pass the proper return code of net IO operations
  http: Add 'post_data', a new option which sets custom HTTP post data
  lavfi: amix: check active input count before calling request_samples
  vp8: move block coeff arithcoder on stack.
  mp3/ac3 probe: search for PES headers to prevent probing MPEG-PS as MP3.

Conflicts:
	libavformat/ac3dec.c
	libavformat/mp3dec.c
	tests/fate/ac3.mak

Merged-by: Michael Niedermayer <michaelni@gmx.at>