Exclude file_posix.cc from iOS build of net/ target

net/net.gyp

Index: net/net.gyp
diff --git a/net/net.gyp b/net/net.gyp
index b9c7dc665b8f0a2483a847e260d5631c6e6e210d..308c98d2be0d7bf94dba92d7eb82e279263f097a 100644
--- a/net/net.gyp
+++ b/net/net.gyp
@@ -1554,6 +1554,9 @@
               '../third_party/nss/nss.gyp:nss',
               'third_party/nss/ssl.gyp:libssl',
             ],
+            'sources!': [
+              'disk_cache/file_posix.cc',
+            ],
             'link_settings': {
               'libraries': [
                 '$(SDKROOT)/System/Library/Frameworks/CFNetwork.framework',
@@ -1562,9 +1565,6 @@
                 '$(SDKROOT)/System/Library/Frameworks/SystemConfiguration.framework',
                 '$(SDKROOT)/usr/lib/libresolv.dylib',
               ],
-              'sources!': [
-                'disk_cache/file_posix.cc',
-              ],
             },
           },
         ],