mpd: bump to version 0.20.18

Also add hash for license file.

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mpd/mpd.hash

@@ -1,2 +1,3 @@
 # Locally calculated after checking pgp signature
-sha256  c69c4f67e665380ea3bbde6cff8958edc85f7cd40e7918ae5ce0a2184ca9eb40  mpd-0.20.15.tar.xz
+sha256  6a582dc2ae90b94ff3853f9ffd7d80b2c2b5fe2e2c35cb1da0b36f3f3dfad434  mpd-0.20.18.tar.xz
+sha256  ab15fd526bd8dd18a9e77ebc139656bf4d33e97fc7238cd11bf60e2b9b8666c6  COPYING

package/mpd/mpd.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 MPD_VERSION_MAJOR = 0.20
-MPD_VERSION = $(MPD_VERSION_MAJOR).15
+MPD_VERSION = $(MPD_VERSION_MAJOR).18
 MPD_SOURCE = mpd-$(MPD_VERSION).tar.xz
 MPD_SITE = http://www.musicpd.org/download/mpd/$(MPD_VERSION_MAJOR)
 MPD_DEPENDENCIES = host-pkgconf boost