Closes https://github.com/MusicPlayerDaemon/MPD/issues/1233

Make sure that ZeroconfDeinit() gets called even if startup fails with
an exception.  Fixes an assertion failure because an Avahi TimerEvent
is still active.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1192

This will allow using Zeroconf in output plugins (preparing for
Snapcast with Zeroconf).

This got lost in commit 5d597a36 (v0.21.19), but it was never
noticed because the state_file_interval was way too short due to
commit 3413d1bf, fixed recently by commit 27cc7b35

clocale is part of C++11.

In practical terms, gcc's libstdc++ comes with its own locale defines
when the libc does not have them.

Also reworked to be dependent on !ANDROID.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

"DEFAULT" is a bad name - all it says is that it's the default value,
but it doesn't say what it means.  The name NOTICE mimics the syslog
level.

Switch to std:: functions. Changed the meson check. Works locally.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Documentation says the limit is 5, but it was really 10 (at least
since 2004).  But since MPD wants to promote using many small clients
idling around, and these clients consume only very few resources, it
seems reasonable to raise this limit's default value.

The former was deprecated with C++14. The standard says they are the same
with one exception:

The header<climits>defines all macros the same as the C standard library
header<limits.h>.

[Note:The types of the constants defined by macros in<climits>are not
required to match the types to which themacros refer.— end note]
Signed-off-by: Rosen Penev <rosenp@gmail.com>

By eliminating GetAnyClient(), we can have instances with no outputs
at all.

Supports suffixes such as "kB" and "MB".