clang/win/gn: Pass -msse flags to clang-cl.exe for skia

skia/BUILD.gn

 # Copyright (c) 2013 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.
 
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 if (current_cpu == "arm") {
   import("//build/config/arm.gni")
 }
@@ skipping 527 matching lines @@
     sources += gypi_skia_pdf.sources
   }
 
   if (is_android && !is_debug) {
     configs -= [ "//build/config/compiler:optimize" ]
     configs += [ "//build/config/compiler:optimize_max" ]
   }
 }
 
 # Separated out so it can be compiled with different flags for SSE.
+# TODO(GYP): This is wrong, it needs one target per arch http://crbug.com/496512
 source_set("skia_opts") {
   cflags = []
   defines = []
 
   if (current_cpu == "x86" || current_cpu == "x64") {
     sources = gypi_skia_opts.sse2_sources + gypi_skia_opts.ssse3_sources +
               gypi_skia_opts.sse41_sources +
               [
                 # Chrome-specific.
                 "ext/convolver_SSE2.cc",
                 "ext/convolver_SSE2.h",
               ]
 
-    if (is_linux || is_mac) {
+    if (!is_win || is_clang) {
       cflags += [ "-msse4.1" ]
-    } else if (is_win) {
+    }
+    if (is_win) {
       defines += [ "SK_CPU_SSE_LEVEL=41" ]
     }
   } else if (current_cpu == "arm") {
     # The assembly uses the frame pointer register (r7 in Thumb/r11 in
     # ARM), the compiler doesn't like that.
     cflags += [ "-fomit-frame-pointer" ]
 
     if (arm_version >= 7) {
       sources = gypi_skia_opts.armv7_sources
       if (arm_use_neon || arm_optionally_use_neon) {
@@ skipping 95 matching lines @@
       "tools/filter_fuzz_stub/filter_fuzz_stub.cc",
     ]
 
     deps = [
       ":skia",
       "//base",
       "//base/test:test_support",
     ]
   }
 }