Reorganize test targets in WebRTC

This CL will lower the number of test targets in WebRTC by:

Add common_audio_unittests and merge the following targets into it (copied from http://review.webrtc.org/1584006):
* resampler_unittests
* signal_processing_unittests
* vad_unittests

Merge into modules_unittests:
* bitrate_controller_unittests
* desktop_capture_unittests
* media_file_unittests
* remote_bitrate_estimator_unittests
* rtp_rtcp_unittests
* paced_sender_unittests

Merge into test_support_unittests:
* channel_transport_unittests

channel_transport.gyp was also removed in favor for test.gyp.

I had to remove a main method from rtcp_format_remb_unittest.cc
since it caused the fileutils.h code to not be able to find the
right project root path in ordrer to provide correct paths
to test files.

Buildbot configuration update will be synced with the commit of this CL.

TEST=trybots
BUG=1843
R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1639004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4213 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/bitrate_controller/bitrate_controller.gypi

@@ -34,24 +34,4 @@
       'msvs_disabled_warnings': [ 4267, ],
     },
   ], # targets
-
-  'conditions': [
-    ['include_tests==1', {
-      'targets' : [
-        {
-          'target_name': 'bitrate_controller_unittests',
-          'type': 'executable',
-          'dependencies': [
-            'bitrate_controller',
-            '<(webrtc_root)/test/test.gyp:test_support_main',
-            '<(DEPTH)/testing/gtest.gyp:gtest',
-          ],
-          'sources': [
-            'bitrate_controller_unittest.cc',
-           ],
-         },
-       ], # targets
-    }], # include_tests
-  ], # conditions
-
 }