For libavcodec 59 support.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1333

Adds the Interface Name as an argument to the *Init functions to make it
possible to select which interface is used by upnp to detect servers.

Currently "nullptr" is passed in to let the upnp library select an
interface, as before.

.. instead of DeferEvent, which is not thread-safe.  This caused
various playback problems, which was initially caused by the
DeferEvent/InjectEvent split in commit 774b4313

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1298

Fixes https://github.com/MusicPlayerDaemon/MPD/discussions/1281

The problem occurred when there was libfmt-dev installed, but it was
too old (e.g. on Debian Buster), and Meson used the wrap fallback.
Those internal MPD libraries where the libfmt dependency was not
declared were still using the old system libfmt headers, which are not
ABI-compatible with MPD's own libfmt build.

This reverts commit 6ed4aff4.  The
Meson wrap is broken on non-x86, because it unconditionally includes
<cpuid.h> which is an x86 only header.

Fixes the build with libexpat from Meson wrap.

Necessary since commit 6acf81d5

make_pair is an old C++98 function that can be replaced by modern
shorter constructs.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Insert an "aformat" filter which converts double-precision to
single-precision.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1235

Merge some duplicate code.

Since AVFilterContext are freed automatically, this wrapper class
serves no purpose.  Let's remove it.

Fixes potential double-free bugs which currently did not occur because
the destructors happened to be called in the right order.

Fixes part 1 of https://github.com/MusicPlayerDaemon/MPD/issues/1235

The type is duplicated otherwise

Found with modernize-use-auto
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1210

Fixes
../git/src/Log.hxx:121:42: error: no member named 'forward' in namespace 'std'
        LogFormat(LogLevel::ERROR, e, fmt, std::forward<Args>(args)...);
Signed-off-by: Khem Raj <raj.khem@gmail.com>

Found with cppcoreguidelines-special-member-functions
Signed-off-by: Rosen Penev <rosenp@gmail.com>