Fix coverage build.

webrtc/build/common.gypi

 # Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 # This file contains common settings for building WebRTC components.
 
@@ skipping 351 matching lines @@
             ],
           }],
           ['mips_dsp_rev==2', {
             'defines': [
               'MIPS_DSP_R1_LE',
               'MIPS_DSP_R2_LE',
             ],
           }],
         ],
       }],
       ['coverage==1 and OS=="linux"', {

[kjellander_webrtc, 2016/04/11 19:53:08]

I think we should add clang==0 here to make it clear that it's GCC's coverage.

[Michael Achenbach, 2016/04/12 08:58:34]

The cflags are valid for both the clang and the gcc coverage builds.

         'cflags': [ '-ftest-coverage',
                     '-fprofile-arcs' ],
+        'ldflags': [ '--coverage' ],

[kjellander_webrtc, 2016/04/11 19:53:08]

Adding this, which seems to be Clang specific, just confuses the user.
We should probably adapt something similar to V8's
https://chromium.googlesource.com/v8/v8/+/master/build/standalone.gypi instead.

See https://bugs.chromium.org/p/chromium/issues/detail?id=568949 for the great
work machenbach@ has done for V8's coverage effort.

[Michael Achenbach, 2016/04/12 08:58:34]

This seems to fix the clang case as described e.g. here:
http://logan.tw/posts/2015/04/28/check-code-coverage-with-clang-and-lcov/

GCC needs 'ldflags': [ '-fprofile-arcs']. If you want to support both, you need
to add clang=1 or clang=0 to the conditions.

[kjellander_webrtc, 2016/04/19 05:31:51]

OK. If it needs more work when/if we decide to setup Clang coverage that's fine
with me.

         'link_settings': { 'libraries': [ '-lgcov' ] },
       }],
       ['os_posix==1', {
         # For access to standard POSIXish features, use WEBRTC_POSIX instead of
         # a more specific macro.
         'defines': [
           'WEBRTC_POSIX',
         ],
       }],
       ['OS=="ios"', {
@@ skipping 116 matching lines @@
           # For access to standard POSIXish features, use WEBRTC_POSIX instead
           # of a more specific macro.
           'defines': [
             'WEBRTC_POSIX',
           ],
         }],
       ],
     },
   }, # target_defaults
 }