Add VP9 codec to VCM and vie_auto_test.

Include VP9 tests in videoprocessor_integrationtests.
Include end-to-end send/receiveVP9 test.

This is the same patch as https://code.google.com/p/webrtc/source/detail?r=7422, which was reverted when rolled into chrome (due to bss size increase). Relanding this again as we now have the clear to get this in:
see https://code.google.com/p/webrtc/issues/detail?id=3932

R=kjellander@webrtc.org, mflodman@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/31829004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7588 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/video_coding/main/source/video_coding.gypi

@@ -17,6 +17,7 @@
         '<(webrtc_root)/modules/video_coding/utility/video_coding_utility.gyp:video_coding_utility',
         '<(webrtc_root)/system_wrappers/source/system_wrappers.gyp:system_wrappers',
         '<(webrtc_vp8_dir)/vp8.gyp:webrtc_vp8',
+        '<(webrtc_vp9_dir)/vp9.gyp:webrtc_vp9',
       ],
       'sources': [
         # interfaces