av_demuxer_iterate() was added in libavformat 58.9.100.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1178

Prevents a possible bug which occurs when the caller-provided open()
function throws; then the "uri" field is never set.

Prevent false negative after the stream was closed automatically after
20 seconds.

From libavformat/mov.c.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1173

This mapping was added 11 years ago in commit 766b9fd4, but FFmpeg
doesn't appear to support it.

These were added 11 years ago in commit 766b9fd4, but I cannot find
any evidence in the FFmpeg repository that these names were ever
supported.  This commit adds the tags as they are currently present in
libavformat/mov.c.

When updating everything, this did work, but if updating only a
subdirectory, the ".mpdignore" in the parents were not used.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1172

Fixes broken libavahi-client timeouts.

Don't propagate MPD-specific compiler flags to subprojects.

Meson adds "-Wpedantic" in warning_level 3 (which is MPD's default).

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1171

Fixes building under GCC 11

That is when meson option b_sanitize is not used

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1168

Fixes -Wformat warnings.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1150