http: Reduce scope of a variable in parse_content_encoding()

Also fixes an unused variable warning with zlib disabled.
w32pthreads: Mark functions in compatibility wrapper as av_unused

This avoids annoying warnings about unused functions. The compatibility
wrapper is designed to provide a complete (stub) API, so some functions
being unused by some files is natural and no reason for a warning.
atomic_win32: Drop unnecessary atomic.h #include

The file does not require atomic.h. Also kills function redefinition warnings.
vfwcap: Replace deprecated av_destruct_packet() by av_free_packet()
mpegvideo: cosmetics: Lowercase ugly uppercase MPV_ function name prefixes
build: Add explanatory comments to (optimization) blocks in the Makefiles
Merge commit '7ccb847f0f1f28199fa254847b91b6e50fb92832'

* commit '7ccb847f0f1f28199fa254847b91b6e50fb92832':
  http: Reduce scope of a variable in parse_content_encoding()

Merged-by: Michael Niedermayer <michaelni@gmx.at>
cosmetics: Write NULL pointer equality checks more compactly

Signed-off-by: Diego Biurrun <diego@biurrun.de>
Merge commit '6baeadd11083774ebd823dd5e1a744c2150a3bfc'

* commit '6baeadd11083774ebd823dd5e1a744c2150a3bfc':
  w32pthreads: Mark functions in compatibility wrapper as av_unused

Conflicts:
	compat/w32pthreads.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '7c371754fbc0dcc23bd00278b147f8095ccc5625'

* commit '7c371754fbc0dcc23bd00278b147f8095ccc5625':
  atomic_win32: Drop unnecessary atomic.h #include

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'a6a27fede94efe48aad1dcc9d5e000d2de71c7b2'

* commit 'a6a27fede94efe48aad1dcc9d5e000d2de71c7b2':
  vfwcap: Replace deprecated av_destruct_packet() by av_free_packet()

Merged-by: Michael Niedermayer <michaelni@gmx.at>
cosmetics: Write NULL pointer inequality checks more compactly

Signed-off-by: Diego Biurrun <diego@biurrun.de>
Fix packet_buffer memory leak in avformat_free_context

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
vformat/utils: call flush_packet_queue() from avformat_free_context()

This avoids some theoretical memleaks

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '835f798c7d20bca89eb4f3593846251ad0d84e4b'

* commit '835f798c7d20bca89eb4f3593846251ad0d84e4b':
  mpegvideo: cosmetics: Lowercase ugly uppercase MPV_ function name prefixes

Conflicts:
	libavcodec/h261dec.c
	libavcodec/intrax8.c
	libavcodec/mjpegenc.c
	libavcodec/mpeg12dec.c
	libavcodec/mpeg12enc.c
	libavcodec/mpeg4videoenc.c
	libavcodec/mpegvideo.c
	libavcodec/mpegvideo.h
	libavcodec/mpegvideo_enc.c
	libavcodec/rv10.c
	libavcodec/x86/mpegvideoenc.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'efd26bedec9a345a5960dbfcbaec888418f2d4e6'

* commit 'efd26bedec9a345a5960dbfcbaec888418f2d4e6':
  build: Add explanatory comments to (optimization) blocks in the Makefiles

Conflicts:
	libavcodec/ppc/Makefile
	libavcodec/x86/Makefile

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'f929ab0569ff31ed5a59b0b0adb7ce09df3fca39'

* commit 'f929ab0569ff31ed5a59b0b0adb7ce09df3fca39':
  cosmetics: Write NULL pointer equality checks more compactly

Conflicts:
	cmdutils.c
	ffmpeg_opt.c
	ffplay.c
	libavcodec/dvbsub.c
	libavcodec/dvdsubdec.c
	libavcodec/dvdsubenc.c
	libavcodec/dxa.c
	libavcodec/libxvid_rc.c
	libavcodec/mpegvideo.c
	libavcodec/mpegvideo_enc.c
	libavcodec/rv10.c
	libavcodec/tiffenc.c
	libavcodec/utils.c
	libavcodec/vc1dec.c
	libavcodec/zmbv.c
	libavdevice/v4l2.c
	libavformat/matroskadec.c
	libavformat/movenc.c
	libavformat/sdp.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '4b1f5e5090abed6c618c8ba380cd7d28d140f867'

* commit '4b1f5e5090abed6c618c8ba380cd7d28d140f867':
  cosmetics: Write NULL pointer inequality checks more compactly

Conflicts:
	libavcodec/dvdsubdec.c
	libavcodec/h263dec.c
	libavcodec/libxvid.c
	libavcodec/rv10.c
	libavcodec/utils.c
	libavformat/format.c
	libavformat/matroskadec.c
	libavformat/segment.c
	libavutil/opt.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Drop remaining unneeded != NULL

Reviewed-by: Clément Bœsch <u@pkh.me>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
ffmpeg: look for encoding options in both avcodec and avformat

This patch is the same as 8a1714ad85dd5defdf1fb2baba9ababebfa47d01 but
applied to encoding. It fixes the current clash of the -password option
between tta decoder and the icecast protocol.