Prepare for removal of source_filter.gypi:

runtime/bin/crypto_macos.cc

Index: runtime/bin/crypto_macos.cc
===================================================================
--- runtime/bin/crypto_macos.cc	(revision 18775)
+++ runtime/bin/crypto_macos.cc	(working copy)
@@ -2,9 +2,12 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-#include <errno.h>
-#include <fcntl.h>
+#include "platform/globals.h"
+#if defined(TARGET_OS_MACOS)
 
+#include <errno.h>  // NOLINT
+#include <fcntl.h>  // NOLINT
+
 #include "bin/fdutils.h"
 #include "bin/crypto.h"
 
@@ -16,3 +19,5 @@
   close(fd);
   return bytes_read == count;
 }
+
+#endif  // defined(TARGET_OS_MACOS)