Bug 1188155: Enable MOZ_GONK_MEDIACODEC in moz.build. r=k17e

--HG--
extra : histedit_source : 2b0d3993540e96b092167f48d1b9966c8e34dac8

dom/media/mediasource/moz.build

@@ -40,6 +40,9 @@ TEST_DIRS += [
     'gtest',
 ]
 
+if CONFIG['MOZ_GONK_MEDIACODEC']:
+    DEFINES['MOZ_GONK_MEDIACODEC'] = True
+
 FAIL_ON_WARNINGS = True
 
 FINAL_LIBRARY = 'xul'