A mutex acts as a memory barrier, and thus "volatile" is not
necessary.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

Has been superseded by the previous commit.

Don't wait for an optimistic write to fail.  This is an improved
workaround for the infamous Raspberry Pi bug (see commit af991765).
It works much better and comes without the negative side effects.  The
old workaround is now obsolete.

On OSX, the configure-flag --enable-osx is used to enable the
unsupported osx output. It sets the HAVE_OSX preprocessor define.

src/output/OpenALOutputPlugin.cxx uses this define to determine wether
it is building on OSX, and imports different headers (which have
nothing to do with the osx output) depending on wether or not it is
set.

See code comment.

Map LogLevel::INFO to G_LOG_LEVEL_INFO, and LogLevel::DEFAULT to
G_LOG_LEVEL_MESSAGE.  Now client connect/disconnect message are only
logged on log_level "secure".

Some, or most, Win32 audio players will pass "icy-metadata:1" to
streaming servers. MPD expects a space between ":" and "1" at this
point, and thus does not send any stream metadata. This applies to
foobar2k and Winamp, for example.

According to forums.radiotoolbox.com/viewtopic.php?t=74 not having
a space there is expected behavior, so maybe MPD could accept
both forms to determine if metadata should be sent or not.

Replaces GLib's g_ascii_strncasecmp().

The new class Path only holds a string pointer without being
responsible for allocation/deallocation.  The FileSystem.hxx library
accepts Path arguments instead of AllocatedPath, to avoid forcing
callers to allocate another string object.

Replacing GLib macros.

Remove the const_cast from HttpdClient.cxx, and avoid one allocation
in ClientRead.cxx.

Micro-optimization.

Prepare to migrate away from GLib.  Currently, we're still using GLib
as a backend.

The MPD core will add this as a prefeix.

Migrate the remaining callers to FatalError().

Replaces GLib's GError.

Remove all #ifdefs.  Old versions of libpulse are not being tested,
and thus I'm removing support.