Only set /ARCH:IA32 on x86 platform

chrome/chrome_installer.gypi

Index: chrome/chrome_installer.gypi
diff --git a/chrome/chrome_installer.gypi b/chrome/chrome_installer.gypi
index b25aa4abd97bf8aac1f0f281e36ec460f137f771..a2dabf6d48b91734f8da1055e9b091fc171b4b4e 100644
--- a/chrome/chrome_installer.gypi
+++ b/chrome/chrome_installer.gypi
@@ -295,9 +295,6 @@
             'installer/setup/uninstall.h',
           ],
           'msvs_settings': {
-            'VCCLCompilerTool': {
-              'EnableEnhancedInstructionSet': '4',  # NoExtensions
-            },
             'VCLinkerTool': {
               'SubSystem': '2',     # Set /SUBSYSTEM:WINDOWS
             },
@@ -357,6 +354,13 @@
                  'branding_dir_100': 'app/theme/default_100_percent/chromium',
               },
             }],
+            ['target_arch=="ia32"', {
+              'msvs_settings': {
+                'VCCLCompilerTool': {
+                  'EnableEnhancedInstructionSet': '4',  # NoExtensions
+                },
+              },
+            }],
           ],
         },
         {