Removing redundant codec unittest targets.

The following targets have been merged into audio_coding_unittests:
* cng_unittests
* g711_unittests
* g722_unittests
* isacfix_unittests
* pcm16b_unittests

Some of them were empty and were created with the assumption they were
needed in order to get code coverage (which was actually not needed).

The following test has been removed since it was empty:
* audio_conference_mixer_unittests

BUG=none
TEST=trybots passing (well, except for the unittests that are removed, they're failing until the try server configuration is updated)

Review URL: https://webrtc-codereview.appspot.com/971008

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3222 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_coding/main/source/audio_coding_module.gypi

@@ -147,6 +147,8 @@
           'type': 'executable',
           'dependencies': [
             'audio_coding_module',
+            'CNG',
+            'iSACFix',
             'NetEq',
             '<(webrtc_root)/common_audio/common_audio.gyp:vad',
             '<(DEPTH)/testing/gtest.gyp:gtest',
@@ -155,6 +157,10 @@
           ],
           'sources': [
              'acm_neteq_unittest.cc',
+             '../../codecs/cng/cng_unittest.cc',
+             '../../codecs/isac/fix/source/filters_unittest.cc',
+             '../../codecs/isac/fix/source/filterbanks_unittest.cc',
+             '../../codecs/isac/fix/source/lpc_masking_model_unittest.cc',
           ],
         }, # audio_coding_unittests
       ],