build: enable clang flags on Windows too

Author: targos

deps/zlib/zlib.gyp

@@ -28,6 +28,11 @@
                   'xcode_settings': {
                     'OTHER_CFLAGS': [ '-mssse3' ],
                   },
+                  'msvs_settings': {
+                    'VCCLCompilerTool': {
+                      'AdditionalOptions': [ '-mssse3' ],
+                    },
+                  },
                 }],
               ],
             }],

tools/v8_gypfiles/toolchain.gypi

@@ -160,6 +160,11 @@
           # -Wno-invalid-offsetof
           'GCC_WARN_ABOUT_INVALID_OFFSETOF_MACRO': 'NO',
         },
+        'msvs_settings': {
+          'VCCLCompilerTool': {
+            'AdditionalOptions': ['-Wno-invalid-offsetof'],
+          },
+        },
       }],
       ['v8_target_arch=="arm"', {
         'defines': [