Some build file cleanup

runtime/bin/secure_socket_unsupported.cc

Index: runtime/bin/secure_socket_unsupported.cc
diff --git a/runtime/bin/secure_socket_unsupported.cc b/runtime/bin/secure_socket_unsupported.cc
index 1cd09d03dfd38f4f3293d555e03fe0b0c0fb6234..a5d6ae3688e84593611ecce995018dad13b3dd0e 100644
--- a/runtime/bin/secure_socket_unsupported.cc
+++ b/runtime/bin/secure_socket_unsupported.cc
@@ -2,6 +2,8 @@
 // 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.
 
+#if defined(DART_IO_SECURE_SOCKET_DISABLED)
+
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 
@@ -175,3 +177,5 @@ CObject* SSLFilter::ProcessFilterRequest(const CObjectArray& request) {
 
 }  // namespace bin
 }  // namespace dart
+
+#endif  // defined(DART_IO_SECURE_SOCKET_DISABLED)