build: Move CFI Windows build config under OS=="win" block.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index b80d0f232226fbc8b655f9427d779576d69f3c4e..18e6df207ff6c32fd98bb950cf66dcb612f0e1ae 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -6236,6 +6236,23 @@
                 '-fsanitize-blacklist=<(cfi_blacklist)',
               ],
             },
+          }],
+          ['_toolset=="target" and _type!="static_library"', {
+            'xcode_settings':  {
+              'OTHER_LDFLAGS': [
+                '-fsanitize=cfi-vcall',
+                '-fsanitize=cfi-derived-cast',
+                '-fsanitize=cfi-unrelated-cast',
+              ],
+            },
+          }],
+        ],
+      },
+    }],
+    ['cfi_vptr==1 and OS=="win"', {
+      'target_defaults': {
+        'target_conditions': [
+          ['_toolset=="target"', {
             'msvs_settings': {
               'VCCLCompilerTool': {
                 'AdditionalOptions': [
@@ -6261,15 +6278,6 @@
               },
             },
           }],
-          ['_toolset=="target" and _type!="static_library"', {
-            'xcode_settings':  {
-              'OTHER_LDFLAGS': [
-                '-fsanitize=cfi-vcall',
-                '-fsanitize=cfi-derived-cast',
-                '-fsanitize=cfi-unrelated-cast',
-              ],
-            },
-          }],
         ],
       },
     }],