memory leaks in av_dict_set()

[Suhwan]

Summary of the bug:
There're memory leaks detected in av_dict_set()
How to reproduce:

% ffmpeg_g -y -i $PoC1 -i $PoC2 -filter_complex acompressor -target dvd -loglevel 0 -c pcm_s24le tmp.dnxhd

ffmpeg version N-95464-g7056ddc0e0 Copyright (c) 2000-2019 the FFmpeg developers
built with clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
configuration: --cc=clang --cxx=clang++ --ld=clang --enable-debug

Here's Valgrind log

==36149== HEAP SUMMARY:
==36149==     in use at exit: 1,046 bytes in 61 blocks
==36149==   total heap usage: 643 allocs, 582 frees, 2,630,129 bytes allocated
==36149== 
==36149== 54 (16 direct, 38 indirect) bytes in 1 blocks are definitely lost in loss record 40 of 44
==36149==    at 0x9FE3E76: memalign (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==36149==    by 0x9FE3F91: posix_memalign (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==36149==    by 0x592F079: av_malloc (mem.c:87)
==36149==    by 0x592F079: av_mallocz (mem.c:238)
==36149==    by 0x58EA3CC: av_dict_set (dict.c:89)
==36149==    by 0x45D36E: new_output_stream (ffmpeg_opt.c:1554)
==36149==    by 0x455A25: new_audio_stream (ffmpeg_opt.c:1860)
==36149==    by 0x4508EC: init_output_filter (ffmpeg_opt.c:2062)
==36149==    by 0x43481F: open_output_file (ffmpeg_opt.c:2187)
==36149==    by 0x42DE5E: open_files (ffmpeg_opt.c:3283)
==36149==    by 0x42DC06: ffmpeg_parse_options (ffmpeg_opt.c:3337)
==36149==    by 0x487BB3: main (ffmpeg.c:4862)
==36149== 
==36149== LEAK SUMMARY:
==36149==    definitely lost: 16 bytes in 1 blocks
==36149==    indirectly lost: 38 bytes in 3 blocks
==36149==      possibly lost: 0 bytes in 0 blocks
==36149==    still reachable: 992 bytes in 57 blocks
==36149==         suppressed: 0 bytes in 0 blocks
==36149== Reachable blocks (those to which a pointer was found) are not shown.
==36149== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==36149== 
==36149== For counts of detected and suppressed errors, rerun with: -v
==36149== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

Please confirm.
Thanks

[Suhwan]

poc1

[Suhwan]

poc2

[mkver]

Fixed in 6f2a3958cfac135c60b509a61a4fd39432d8f9a9.