Undo accidental change to common.gypi.

build/common.gypi

 # Copyright (c) 2009 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.
 
 {
   'variables': {
     # .gyp files should set chromium_code to 1 if they build Chromium-specific
     # code, as opposed to external code.  This variable is used to control
     # such things as the set of warnings to enable, and whether warnings are
     # treated as errors.
@@ skipping 494 matching lines @@
           '_HAS_TR1=0',
         ],
         'msvs_system_include_dirs': [
           '<(DEPTH)/third_party/platformsdk_win2008_6_1/files/Include',
           '$(VSInstallDir)/VC/atlmfc/include',
         ],
         'msvs_cygwin_dirs': ['../third_party/cygwin'],
         'msvs_disabled_warnings': [4396, 4503, 4819],
         'msvs_settings': {
           'VCCLCompilerTool': {
-            'AdditionalOptions': '/MP',
             'MinimalRebuild': 'false',
             'ExceptionHandling': '0',
             'BufferSecurityCheck': 'true',
             'EnableFunctionLevelLinking': 'true',
             'RuntimeTypeInfo': 'false',
             'WarningLevel': '3',
             'WarnAsError': 'true',
             'DebugInformationFormat': '3',
           },
           'VCLibrarianTool': {
@@ skipping 84 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',
   },
 }