asterisk: default astdatadir to /usr/lib/asterisk

This is needed in order for asterisk to find the sound files we provide
(and I found adding a symlink from the sounds dir to /var/lib/asterisk/
being just too ugly). As it changes only the default configuration, I
guess this is fine without increasing PKG_RELEASE.

package/asterisk/Makefile

@@ -174,6 +174,7 @@ do-install: ${SUB_INSTALLS-m} ${SUB_INSTALLS-y}
 		rm -f gtalk.conf ; \
 		rm -f skinny.conf ; \
 		rm -f dundi.conf ; \
+		echo -e '/^astdatadir =/s/var/usr/\nwq\n' | ed asterisk.conf ; \
 	)
 	${INSTALL_DATA} ./files/modules.conf $(IDIR_ASTERISK)/etc/asterisk/
 	$(SED) 's|/var/lib/asterisk|/usr/lib/asterisk|g' \