lavc: call av_frame_unref() instead of avcodec_get_frame_defaults().

avcodec_get_frame_defaults() will be deprecated.
avplay: do not call avcodec_get_frame_defaults().

avcodec_decode_audio4() will reset the frame itself.
mpegvideo: remove an unneeded call to avcodec_get_frame_defaults().

ff_mpeg_unref_picture() already resets the frame.
mpegvideo: call av_frame_unref() instead of avcodec_get_frame_defaults().

This is a temporary workaround to allow deprecating
avcodec_get_frame_defaults(). The proper solution will be using a
properly allocated AVFrame in Picture.
lavf: remove an unneeded call to avcodec_get_frame_defaults().

avcodec_decode_*() resets the frame itself.
api-example: remove an unneeded call to avcodec_get_frame_defaults().

avcodec_decode_audio4() resets the frame itself.
h264: call av_frame_unref() instead of avcodec_get_frame_defaults().

This is a temporary workaround to allow deprecating
avcodec_get_frame_defaults(). The proper solution will be using a
properly allocated AVFrame in Picture.
lavc: deprecate avcodec_get_frame_defaults().

Also bump libavcodec micro and add an APIchanges entry saying that
av_frame_* should now be used instead of the lavc AVFrame functions.
rtspdec: Fix keep-alive request for ACTi cameras

Some ACTi cameras fail if "*" is passed as the URI.

Signed-off-by: Ismael Luceno <ismael.luceno@corp.bluecherry.net>
Signed-off-by: Martin Storsjö <martin@martin.st>
mp3adu: Set the channel layout properly

This fixes decoding, broken since 7e35037.

This is similar to what was done for the normal mp3 decoder in
f4a86bc9.

Signed-off-by: Martin Storsjö <martin@martin.st>
parseutils: fix discarding const attribute warning
rtsp: suppress a incompatible pointer types warning
img2: add stereo 3d still picture file extensions
changelog: drop redundant new attribute
mpegts: add HEVC registration descriptor
build: Do not add -g to HOSTCFLAGS

The flag is not unconditionally added to CFLAGS either and the
programs built on the host do not get habitually fed to a debugger.
configure: Detect newer (>=4.1) versions of MinGW32

The MinGW32 project is deprecating its old version macros.
configure: Add -D__USE_MINGW_ANSI_STDIO=1 to CPPFLAGS on MinGW32

This enables a more C99-compliant implementation of printf et al.
build: Merge pthreads/w32threads OBJS declarations
avutil: Add deprecation ifdefs around obsolete intfloat code

This long-deprecated code should disappear at the next version bump.