rtc_use_h264 flag for building OpenH264/FFmpeg

webrtc/modules/video_coding/codecs/h264/h264.gypi

Index: webrtc/modules/video_coding/codecs/h264/h264.gypi
diff --git a/webrtc/modules/video_coding/codecs/h264/h264.gypi b/webrtc/modules/video_coding/codecs/h264/h264.gypi
index a20865c3aaa55ceb414dfa5ce3c7981f6183a146..8b8318cbd92882f70a9de883617f5dc785b15ea9 100644
--- a/webrtc/modules/video_coding/codecs/h264/h264.gypi
+++ b/webrtc/modules/video_coding/codecs/h264/h264.gypi
@@ -23,6 +23,14 @@
             'h264_objc.mm',
           ],
         }],
+        ['use_h264==1', {
+          # Dependency for sake of compiling The dependencies will be used for
+          # real as soon as https://codereview.webrtc.org/1306813009/ lands.
+          'dependencies': [
+            '<(DEPTH)/third_party/ffmpeg/ffmpeg.gyp:ffmpeg',
+            '<(DEPTH)/third_party/openh264/openh264.gyp:openh264_encoder',
+          ],
+        }],
       ],
       'sources': [
         'h264.cc',