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

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

clang-tidy reports this is trivially copyable and thus std::move has no
effect.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Almost all callers have string literal, and the length is known at
compile time.

With libfmt versions older than 7, this leads to an endless recursion
between Error() and FmtError(), resulting in a crash due to stack
overflow.  D'oh!

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1295

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1115

Fixes -Wformat warnings.

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

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1156

Shorter.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Preparing for a variant of TimerEvent with coarse 1-second
granularity, but cheaper (with a timer wheel).

Increasing the protocol version to 0.22.4 to allow clients to detect
this feature.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1038

Shorter.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

The ones in std have overloads for const char/char.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

The former is deprecated with C++14. The standard says both are the same:

The contents and meaning of the header<cstddef>are the same as the C
standard library header<stddef.h>,except that it does not declare the type
wchar_t, that it also declares the type byte and its associated
operations (21.2.5), and as noted in 21.2.3 and 21.2.4.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

The former was deprecated in C++14. The Standard says they are the same:

The contents of the header<cstdarg>are the same as the C standard library
header<stdarg.h>, with the following changes: The restrictions that ISO C
places on the second parameter to the va_start macro in header<stdarg.h>
are different in this International Standard. The parameter parmN is the
rightmost parameter in the variable parameter list of the function
definition (the one just before the...).219If the parameter parmN is a
pack expansion (17.5.3) or an entity resulting from a lambda capture
(8.1.5), the program is ill-formed, no diagnostic required. If the
parameter parmN is of a reference type, or of a type that is not
compatible with the type that results when passing an argument for which
there is no parameter, the behavior is undefined.

Also changed va_list to the std:: namespace version, which is the same.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

The former was deprecated with C++14.

According to the C++11 and C++17 standards, both files are identical.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Fixes assertion failure.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/774

Found with performance-move-const-arg
Signed-off-by: Rosen Penev <rosenp@gmail.com>

Make idle events per-partition, but leave Instance::EmitIdle() and its
underlying idle_monitor which broadcasts idle events to all
partitions.

For efficient traversal within one partition, e.g. for distributing
partition-local idle events.