add OS X configure stuff and added a skeleton audioOutput plugin for OS X

git-svn-id: https://svn.musicpd.org/mpd/trunk@3074 09075e82-0dd4-0310-85a5-a0d7c8717e4f

configure.ac

@@ -102,6 +102,13 @@ AP_maGiC_VALUE
 )
 fi
 
+enable_osx=no
+case $host in
+	*-darwin*)
+                AC_DEFINE(HAVE_OSX, 1, [Define for compiling OS X support])
+		enable_osx=yes ;;
+esac
+
 if test x$enable_ogg = xno; then
 	AC_MSG_WARN("disabling shout streaming support since vorbis was not found")
 fi
@@ -582,6 +589,12 @@ else
 	echo "Playing audio via ALSA ........disabled"
 fi
 
+if test x$enable_osx = xyes; then
+	echo "Playing audio on OS X .........enabled"
+else
+	echo "Playing audio on OS X .........disabled"
+fi
+
 if test x$enable_shout = xyes; then
 	echo "Streaming through shout .......enabled"
 else