[NaCl SDK] nacl_io: implement set/getsockopt for TCP_NODELAY.

native_client_sdk/src/libraries/nacl_io/mount_node_socket.cc

Index: native_client_sdk/src/libraries/nacl_io/mount_node_socket.cc
diff --git a/native_client_sdk/src/libraries/nacl_io/mount_node_socket.cc b/native_client_sdk/src/libraries/nacl_io/mount_node_socket.cc
index f5c20c1b0a5092cb1d370db4f7415a16bb9b892f..d137e0706b7cafabd86ed9ec69642b1572264736 100644
--- a/native_client_sdk/src/libraries/nacl_io/mount_node_socket.cc
+++ b/native_client_sdk/src/libraries/nacl_io/mount_node_socket.cc
@@ -226,6 +226,8 @@ Error MountNodeSocket::GetSockOpt(int lvl,
   if (lvl != SOL_SOCKET)
     return ENOPROTOOPT;
 
+  AUTO_LOCK(node_lock_);
+
   int value = 0;
   socklen_t value_len = 0;
   void* value_ptr = NULL;
@@ -270,6 +272,8 @@ Error MountNodeSocket::SetSockOpt(int lvl,
   if (lvl != SOL_SOCKET)
     return ENOPROTOOPT;
 
+  AUTO_LOCK(node_lock_);
+
   switch (optname) {
     case SO_REUSEADDR: {
       // SO_REUSEADDR is effectivly always on since we can't