mpd: Update to latest (0.18.21)

Signed-off-by: Ted Hess <thess@kitschensync.net>

sound/mpd/Makefile

@@ -1,5 +1,5 @@
 #
-# Copyright (C) 2007-2014 OpenWrt.org
+# Copyright (C) 2007-2015 OpenWrt.org
 #
 # This is free software, licensed under the GNU General Public License v2.
 # See /LICENSE for more information.
@@ -8,12 +8,12 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=mpd
-PKG_VERSION:=0.18.20
+PKG_VERSION:=0.18.21
 PKG_RELEASE:=1
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
 PKG_SOURCE_URL:=http://www.musicpd.org/download/mpd/0.18/
-PKG_MD5SUM:=88ba076000e13dbf094b3e32a6472944
+PKG_MD5SUM:=945879f55acc256d30a5f69787338ceb
 PKG_MAINTAINER:=Ted Hess <thess@kitschensync.net>
 
 PKG_LICENSE:=GPL-2.0