avconv: use a local variable for OutputFile in open_output_file().

This is shorter and more readable.
avconv: use a local variable for InputFile in open_input_file().

This is shorter and more readable.
FATE: remove the -dct option from some decoding tests.

It is an encoding option, it has no effect when applied to decoding.
FATE: replace -vb with -b:v

The -{vas}<option> syntax is now obsolete and deprecated, and has never
been documented or encouraged.
avconv: fix a typo
avconv: do not silently ignore unused codec AVOptions.

Print an error and abort when the option is of the wrong type (decoding
for output file or vice versa), since this could never be correct for
any input or output configuration.

Print a warning and continue when the option is of the correct type,
just unused, so same commandlines can be reused for different kinds of
input or output files.
atomic: Exclude the unsupported implementation headers from checkheaders

Signed-off-by: Martin Storsjö <martin@martin.st>
libmp3lame: use the correct remaining buffer size when flushing

CC:libav-stable@libav.org
png: use av_mallocz_array() for the zlib zalloc function

Fixes valgrind uninitialized memory errors when decoding png.

CC:libav-stable@libav.org
lavc: remove disabled FF_API_OLD_DECODE_AUDIO cruft
lavc: remove disabled FF_API_MPV_GLOBAL_OPTS cruft
lavc: remove disabled FF_API_OLD_ENCODE_AUDIO cruft
lavc: remove disabled FF_API_COLOR_TABLE_ID cruft
lavc: remove disabled FF_API_SUB_ID cruft
atomic: fix CAS with armcc.

On the current code, armcc will fail with:
"libavutil/atomic_gcc.h", line 52: Error:  #2771: first argument must be
a pointer to integer or enumeration type
lavc: remove disabled FF_API_OLD_ENCODE_VIDEO cruft
lavc: remove disabled FF_API_INTER_THRESHOLD cruft
lavc: remove disabled FF_API_DSP_MASK cruft
lavc: remove disabled FF_API_FIND_BEST_PIX_FMT cruft
lavc: remove disabled FF_API_CODEC_ID cruft