Merge remote-tracking branch 'qatar/master'

* qatar/master:
  configure: make executable again
  LATM/AAC: Free previously initialized context on reinit.
  configure: Do not unconditionally add -Wall to host CFLAGS.
  configure: Set OS/2 objformat to a.out.
  Add support for a.out object format to assembler macros.
  fate: disable threading for encoding
  fate: add comment field
  fate: allow overriding default build and install dirs
  mpegtsenc: Add an AVClass pointer to the private data
  mpegaudio: clean up #includes
  mpegaudio: move all header parsing to mpegaudiodecheader.[ch]

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