cdio_get_devices_with_cap() can return nullptr if no drive was found,
or it can instead return an empty list.  The latter caused MPD to
crash.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1532

If the PipeWire output has not yet been enabled and no thread_loop has
been created yet, a nullptr dereference in SetVolume() was possible
because nullptr was passed to pw_thread_loop_lock().

If a mixer is not open, rethrow the original exception each time
setting the volume is requested.  This further improves error messages
sent to MPD clients.

If a mixer is "global", it is available even if the output isn't
open.  However, since the check was changed from IsEnabled() to
IsReallyEnabled(), enabled outputs have not yet been used have not
been "really" enabled yet, preventing using the mixer.

Fixes a regression by commit 35dbc1a9
(part of https://github.com/MusicPlayerDaemon/MPD/pull/1480).

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1563

This reveals more about the nature of an error instead of just
returning "problems setting volume".

libfmt version 9 broke the API by removing fmt::make_args_checked().

Fixes https://bugs.debian.org/1014543

Since PipeWire 0.3.53, control names can apparently be nulled, leading
to crashes in applications assertion that the string cannot be
nullptr.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1558

This fixes a std::terminate() crash in the CURL storage plugin when
PropfindOperation::OnHeaders() throws an exception after receiving a
non-207 status.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1559

Fixes Android build failure with NDK r25 beta4 because "vulkan_beta.h"
was not found.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1536

`playlist_plugin` blocks use `name` to identify the plugins.

This was an experiment, but I decided I don't need that.

The build has been failing for a week or two because the package lists
in the image are outdated.

strlen() and strcpy() are provided by the <string.h> and <cstring>
headers (as functions in global and std namespaces, respectively).

Compilers MAY provide an implementation for either of the functions
without including the extra header but the existence of a declaration
without the header is not assured.