require m-s-d 1.21.1 due to new control-center key in schema

Author: monsta

configure.ac

@@ -62,7 +62,7 @@ AC_SUBST(SCREENSAVER_LIBS)
 GLIB_REQUIRED=2.50.0
 GTK_REQUIRED=3.22.0
 MARCO_REQUIRED=1.17.0
-MSD_REQUIRED=1.17.0
+MSD_REQUIRED=1.21.1
 MATEKBD_REQUIRED=1.17.0
 MATE_DESKTOP_REQUIRED=1.21.2
 APPINDICATOR_REQUIRED=0.0.13