Added release_extra_cflags only to the target compiles.

build/common.gypi

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1739 matching lines @@
             # Note that this is a three-way bool, where 0 means to pick up
             # the default setting, 1 is off and 2 is on.
             'RandomizedBaseAddress': 1,
           },
           'VCResourceCompilerTool': {
             'PreprocessorDefinitions': ['_DEBUG'],
           },
         },
         'conditions': [
           ['OS=="linux"', {
-            'cflags': [
-              '<@(debug_extra_cflags)',
+            'target_conditions': [
+              ['_toolset=="target"', {
+                'cflags': [
+                  '<@(debug_extra_cflags)',
+                ],
+              }],
             ],
           }],
           ['release_valgrind_build==0', {
             'xcode_settings': {
               'OTHER_CFLAGS': [
                 '-fstack-protector-all',  # Implies -fstack-protector
               ],
             },
           }],
         ],
@@ skipping 70 matching lines @@
           }, {
             'defines': [
               'DYNAMIC_ANNOTATIONS_ENABLED=1',
               'WTF_USE_DYNAMIC_ANNOTATIONS=1',
             ],
           }],
           ['win_use_allocator_shim==0', {
             'defines': ['NO_TCMALLOC'],
           }],
           ['OS=="linux"', {
-            'cflags': [
-             '<@(release_extra_cflags)',
+            'target_conditions': [
+              ['_toolset=="target"', {
+                'cflags': [
+                  '<@(release_extra_cflags)',
+                ],
+              }],
             ],
           }],
         ],
       },
       #
       # Concrete configurations
       #
       'Debug': {
         'inherit_from': ['Common_Base', 'x86_Base', 'Debug_Base'],
       },
@@ skipping 1263 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }