Don't pass /safeseh to the linker when using clang on Windows

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 4524 matching lines @@
                   '/safeseh',
                   '/dynamicbase',
                   '/ignore:4199',
                   '/ignore:4221',
                   '/nxcompat',
                 ],
                 'conditions': [
                   ['asan==0', {
                     'AdditionalOptions': ['/largeaddressaware'],
                   }],
+                  ['clang==1', {
+                    'AdditionalOptions!': ['/safeseh'],
+                  }],
                 ],
               },
             },
           },
           'x64_Base': {
             'msvs_settings': {
               'VCLinkerTool': {
                 'AdditionalOptions': [
                   # safeseh is not compatible with x64
                   '/dynamicbase',
@@ skipping 127 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',
   },
 }