mpd: update to 0.21.25

pulseaudio-daemon depends on alsa-lib, which depends on @AUDIO_SUPPORT.
Enables -full on platforms lacking AUDIO_SUPPORT.

Simplified LDFLAGS slighly.

Removed pointless ICU dependency. I managed to patch meson.build to fix
iconv compilation. The original error was that without the header, it
was prefixing the iconv check with __buildin_ , which does not work
with uClibc-ng.

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

sound/mpd/patches/010-iconv.patch

@@ -0,0 +1,11 @@
+--- a/src/lib/icu/meson.build
++++ b/src/lib/icu/meson.build
+@@ -18,7 +18,7 @@ if icu_dep.found()
+     'Init.cxx',
+   ]
+ elif not get_option('iconv').disabled()
+-  have_iconv = compiler.has_function('iconv')
++  have_iconv = compiler.has_function('iconv', prefix : '#include <iconv.h>')
+   conf.set('HAVE_ICONV', have_iconv)
+   if not have_iconv and get_option('iconv').enabled()
+     error('iconv() not available')