Bug 1103820 - Support new android version. r=mwu

b2g/app/moz.build

@@ -58,7 +58,7 @@ if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'gonk':
         'cutils',
     ]
     OS_LIBS += CONFIG['MOZ_ZLIB_LIBS']
-    if CONFIG['ANDROID_VERSION'] in ('17', '18', '19'):
+    if CONFIG['ANDROID_VERSION'] in ('17', '18', '19', '21'):
         OS_LIBS += [
             'gui',
             'suspend',