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

[[maybe_unused]] (introduced in C++17) is standard C++.

https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused
says that this is equivalent to the GNU unused attribute.
Signed-off-by: Rosen Penev <rosenp@gmail.com>

The former is deprecated by C++14. It's also functionally the same.

From the standard:

19.4
The header<cerrno>is described in Table 43. Its contents are the same as
the POSIX header<errno.h>,except that errno shall be defined as a macro.
[Note: The intent is to remain in close alignment with the POSIX
standard.] A separate errno value shall be provided for each thread.
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>

This is still needed for GTest 1.8.0 (Travis / Ubuntu Bionic).

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

One basic library without dependencies, and one with heavy
dependencies like libsamplerate.

Prevents compiling those sources many times, once for each debug
program using it.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/685

And allow "Z" suffix after date.