Log Message:
ffmpeg3: update to 3.4.6.

version 3.4.6:
- avcodec/hevcdec: Avoid only partly skiping duplicate first slices
- lavc/bmp: Avoid a heap buffer overwrite for 1bpp input.
- avcodec/truemotion2: Fix integer overflow in tm2_null_res_block()
- avcodec/dfa: Check the chunk header is not truncated
- avcodec/dvbsubdec: Check object position
- avcodec/cdgraphics: Use ff_set_dimensions()
- avformat/gdv: Check fps
- avcodec/scpr: Fix use of uninitialized variable
- avcodec/qpeg: Limit copy in qpeg_decode_intra() to the available bytes
- avcodec/aic: Check remaining bits in aic_decode_coeffs()
- avcodec/gdv: Check for truncated tags in decompress_5()
- avcodec/bethsoftvideo: Check block_type
- avcodec/jpeg2000dwt: Fix integer overflow in dwt_decode97_int()
- avcodec/error_resilience: Use a symmetric check for skipping MV estimation
- avcodec/mlpdec: Insuffient typo
- avcodec/zmbv: obtain frame later
- avcodec/jvdec: Check available input space before decode8x8()
- avcodec/h264_direct: Fix overflow in POC comparission
- avformat/webmdashenc: Check id in adaption_sets
- avformat/http: Fix Out-of-Bounds access in process_line()
- avformat/ftp: Fix Out-of-Bounds Access and Information Leak in ftp.c:393
- avcodec/htmlsubtitles: Fixes denial of service due to use of sscanf in inner \ 
loop for handling braces
- avcodec/htmlsubtitles: Fixes denial of service due to use of sscanf in inner \ 
loop for tag scaning
- avformat/matroskadec: Do not leak queued packets on sync errors
- avformat/mov: Do not use reference stream in mov_read_sidx() if there is no \ 
reference stream
- avcodec/sbrdsp_fixed.c: remove input value limit for sbr_sum_square_c()
- avformat/mov: validate chunk_count vs stsc_data
- avformat/mov.c: require tfhd to begin parsing trun
- avcodec/pgssubdec: Check for duplicate display segments
- avformat/rtsp: Check number of streams in sdp_parse_line()
- avformat/rtsp: Clear reply in every iteration in ff_rtsp_connect()
- avcodec/fic: Check that there is input left in fic_decode_block()
- avcodec/tiff: Check for 12bit gray fax
- avutil/imgutils: Optimize memset_bytes() by using av_memcpy_backptr()
- avutil/mem: Optimize fill32() by unrolling and using 64bit
- configure: bump year
- avcodec/diracdec: Check component quant
- avcodec/tests/rangecoder: initialize array to avoid valgrind warning
- avcodec/h264_slice: Fix integer overflow in implicit_weight_table()
- avcodec/exr: set layer_match in all branches
- avcodec/exr: Check for duplicate channel index
- avcodec/4xm: Fix returned error codes
- avcodec/v4l2_m2m: fix cant typo
- avcodec/mjpegbdec: Fix some misplaced {} and spaces
- avformat/wvdec: detect and error out on WavPack DSD files
- avcodec/mips: Fix failed case: hevc-conformance-AMP_A_Samsung_* when enable msa
- avcodec/fic: Fail on invalid slice size/off
- postproc/postprocess_template: remove FF_REG_sp from clobber list
- postproc/postprocess_template: Avoid using %4 for the threshold compare
- avcodec/rpza: Check that there is enough data for all the blocks
- avcodec/rpza: Move frame allocation to a later point
- avcodec/avcodec: Document the data type for AV_PKT_DATA_MPEGTS_STREAM_ID
- avformat/mpegts: Fix side data type for stream id
- tests/fate/filter-video: increase fuzz for fate-filter-refcmp-psnr-rgb
- avcodec/mjpegdec: Fix indention of ljpeg_decode_yuv_scan()
- lavf/id3v2: fail read_apic on EOF reading mimetype
- avformat/nutenc: Document trailer index assert better
- lavf/mov: ensure only one tkhd per trak
- avcodec/ppc/hevcdsp: Fix build failures with powerpc-linux-gnu-gcc-4.8 with \ 
--disable-optimizations
- avcodec/msvideo1: Check for too small dimensions
- avcodec/wmv2dec: Skip I frame if its smaller than 1/8 of the minimal size
- avcodec/msmpeg4dec: Skip frame if its smaller than 1/8 of the minimal size
- avcodec/truemotion2rt: Fix rounding in input size check
- avcodec/truemotion2: fix integer overflows in tm2_low_chroma()
- avcodec/pngdec: Check compression method
- fftools/ffmpeg: Repair reinit_filter feature
- avcodec/shorten: Fix integer overflow with offset
- avcodec/cavsdec: Propagate error codes inside decode_mb_i()
- avcodec/mpegaudio_parser: Consume more than 0 bytes in case of the unsupported \ 
mp3adu case
- avcodec/hevcdec: decode at most one slice reporting being the first in the picture
- avfilter/af_silenceremove: fix possible crash if supplied duration is negative