Merge remote branch 'qatar/master'

* qatar/master:
  APIChanges: document git revision for CODEC_CAP_SLICE_THREADS addition.
  Introduce slice threads flag.
  FATE: allow forcing thread-type when doing threaded fate runs.
  Use av_log_ask_for_sample() where appropriate.
  error: sort, pack, and align error code and string definitions
  The stabilization period after version bumps should be one month, not one week.
  applehttp: Expose the stream bitrate via metadata
  doc: Add some initial docs on the applehttp demuxer
  Provide a fallback version of the libm function trunc
  libavdevice: Define _XOPEN_SOURCE for usleep
  lavc: provide deprecated avcodec_thread_init until next major version
  lavc: provide the opt.h header until the next bump
  error: change AVERROR_EOF value
  error: remove AVERROR_NUMEXPECTED
  error: add error code AVERROR_OPTION_NOT_FOUND, and use it in opt.c

Conflicts:
	libavcodec/h264.c
	libavutil/error.c
	libavutil/error.h

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

doc/APIchanges

@@ -1,5 +1,6 @@
-Never assume the API of libav* to be stable unless at least 1 week has passed since
-the last major version increase.
+Never assume the API of libav* to be stable unless at least 1 month has passed
+since the last major version increase.
+
 The last version increases were:
 libavcodec:  2011-04-18
 libavdevice: 2011-04-18
@@ -12,6 +13,9 @@ libavutil:   2011-04-18
 
 API changes, most recent first:
 
+2011-04-21 - 94f7451 - lavc 53.1.0 - avcodec.h
+  Add CODEC_CAP_SLICE_THREADS for codecs supporting sliced threading.
+
 2011-04-15 - lavc 52.120.0 - avcodec.h
   AVPacket structure got additional members for passing side information:
     4de339e introduce side information for AVPacket