Linux: fix scons build so that libssl gets the right headers.

net/socket/ssl_client_socket_nss.cc

Index: net/socket/ssl_client_socket_nss.cc
diff --git a/net/socket/ssl_client_socket_nss.cc b/net/socket/ssl_client_socket_nss.cc
index c013ed8bc10f04b1c41db369d2048f8109c8438f..f6a745e3d9246190527e349762e02aaf971cb153 100644
--- a/net/socket/ssl_client_socket_nss.cc
+++ b/net/socket/ssl_client_socket_nss.cc
@@ -312,6 +312,8 @@ int SSLClientSocketNSS::InitializeSSLOptions() {
   rv = SSL_OptionSet(nss_fd_, SSL_ENABLE_DEFLATE, PR_TRUE);
   if (rv != SECSuccess)
      LOG(INFO) << "SSL_ENABLE_DEFLATE failed.  Old system nss?";
+#else
+#error This is a temporary hack to check that the builders are using the correct header files. It will be removed once a build has finished.
 #endif
 
 #ifdef SSL_NEXT_PROTO_NEGOTIATED