Set 'gcc_version' to 0 for Clang/ASan/TSan builds.

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 825 matching lines @@
         'windows_sdk_path%': '<(windows_sdk_default_path)',
       }, {
         'windows_sdk_path%': 'C:/Program Files (x86)/Windows Kits/8.0',
       }],
       ['OS=="win" and "<!(python <(DEPTH)/build/dir_exists.py <(directx_sdk_default_path))"=="True"', {
         'directx_sdk_path%': '<(directx_sdk_default_path)',
       }, {
         'directx_sdk_path%': '$(DXSDK_DIR)',
       }],
       ['os_posix==1 and OS!="mac" and OS!="ios"', {
-        # This will set gcc_version to XY if you are running gcc X.Y.*.
-        # This is used to tweak build flags for gcc 4.4.
-        'gcc_version%': '<!(python <(DEPTH)/build/compiler_version.py)',
         # Figure out the python architecture to decide if we build pyauto.
         'python_arch%': '<!(<(DEPTH)/build/linux/python_arch.sh <(sysroot)/usr/<(system_libdir)/libpython<(python_ver).so.1.0)',
         'conditions': [
+          # TODO(glider): set clang to 1 earlier for ASan and TSan builds so
+          # that it takes effect here.
+          ['clang==0 and asan==0 and tsan==0', {
+            # This will set gcc_version to XY if you are running gcc X.Y.*.
+            # This is used to tweak build flags for gcc 4.5.
+            'gcc_version%': '<!(python <(DEPTH)/build/compiler_version.py)',
+          }, {
+            'gcc_version%': 0,
+          }],
           ['branding=="Chrome"', {
             'linux_breakpad%': 1,
           }],
           # All Chrome builds have breakpad symbols, but only process the
           # symbols from official builds.
           ['(branding=="Chrome" and buildtype=="Official")', {
             'linux_dump_symbols%': 1,
           }],
         ],
       }],  # os_posix==1 and OS!="mac" and OS!="ios"
@@ skipping 2426 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',
   },
 }