Make sure binutils values are always defined.

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 1164 matching lines @@
     # And if we want to dump symbols for Breakpad-enabled builds.
     'linux_dump_symbols%': 0,
     # And if we want to strip the binary after dumping symbols.
     'linux_strip_binary%': 0,
     # Strip the test binaries needed for Linux reliability tests.
     'linux_strip_reliability_tests%': 0,
     # If we want stack unwind support for backtrace().
     'debug_unwind_tables%': 1,
     'release_unwind_tables%': 1,
 
+    # Override where to find binutils
+    'binutils_version%': 0,
+    'binutils_dir%': '',
+
     # Enable TCMalloc.
     # TODO(dmikurube): Change Linux default of use_allocator to "tcmalloc".
     # TODO(dmikurube): Change Android default of use_allocator to "none".
     # TODO(dmikurube): Kill {linux|android}_use_tcmalloc. http://crbug.com/345554
     # {linux|android}_use_tcmalloc are to be replaced with use_allocator.
     # They are now used only if use_allocator=="see_use_tcmalloc" (default).
     # TODO(dmikurube): Assert when {linux|android}_use_tcmalloc is explicitly specified.
     'linux_use_tcmalloc%': 1,
     'android_use_tcmalloc%': 0,
     'use_allocator%': 'see_use_tcmalloc',
@@ skipping 4054 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',
   },
 }