Fix unknown option '-msse2' warning

R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/43169004

Cr-Commit-Position: refs/heads/master@{#9016}

webrtc/modules/audio_processing/BUILD.gn

@@ -223,7 +223,9 @@ if (current_cpu == "x86" || current_cpu == "x64") {
       "aec/aec_rdft_sse2.c",
     ]
 
-    cflags = [ "-msse2" ]
+    if (is_posix) {
+      cflags = [ "-msse2" ]
+    }
 
     configs += [ "../..:common_config" ]
     public_configs = [ "../..:common_inherited_config" ]

webrtc/modules/audio_processing/audio_processing.gypi

@@ -232,10 +232,14 @@
             'aec/aec_core_sse2.c',
             'aec/aec_rdft_sse2.c',
           ],
-          'cflags': ['-msse2',],
-          'xcode_settings': {
-            'OTHER_CFLAGS': ['-msse2',],
-          },
+          'conditions': [
+            ['os_posix==1', {
+              'cflags': [ '-msse2', ],
+              'xcode_settings': {
+                'OTHER_CFLAGS': [ '-msse2', ],
+              },
+            }],
+          ],
         },
       ],
     }],