lavfi: add const to the AVFilter parameter of avfilter_graph_create_filter()

This function should never modify the filter.
avconv: improve some variable names

'filter' is too generic, since the functions in question deal with
several filters.

Also add const qualifiers to those variables.
aac: Check init_get_bits return value

Some code paths can call it with invalid length.

CC: libav-stable@libav.org
aac: Forward errors properly in aac_decode_frame_int

Incidentally also remove a warning.
mxfenc: switch to av_reallocp_array() and check allocation errors

Signed-off-by: Anton Khirnov <anton@khirnov.net>
Merge commit '77cc958f60f73963be4281d6e82ef81707e40c26'

* commit '77cc958f60f73963be4281d6e82ef81707e40c26':
  lavfi: add const to the AVFilter parameter of avfilter_graph_create_filter()

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '51fc88e7467169031b20b9983d80456b893a9fa3'

* commit '51fc88e7467169031b20b9983d80456b893a9fa3':
  avconv: improve some variable names

Conflicts:
	ffmpeg_filter.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '71953ebcf94fe4ef316cdad1f276089205dd1d65'

* commit '71953ebcf94fe4ef316cdad1f276089205dd1d65':
  aac: Check init_get_bits return value

Conflicts:
	libavcodec/aacdec.c

See: 73abc3a634d84e4cc8951787323b594c5476e4a8

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'a10c4ce24bd4a0dd557d5849aa53a0cc74677808'

* commit 'a10c4ce24bd4a0dd557d5849aa53a0cc74677808':
  aac: Forward errors properly in aac_decode_frame_int

Conflicts:
	libavcodec/aacdec.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  mxfenc: switch to av_reallocp_array() and check allocation errors

Merged-by: Michael Niedermayer <michaelni@gmx.at>
avformat/latmenc: use init_get_bits8()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/ra144dec: use init_get_bits8()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/diracdec: use init_get_bits8()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/eatgq: use init_get_bits8()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/takdec: use init_get_bits8()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/tta: use init_get_bits8()

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