lwm_nop fixed to not emit warnings on g++; locking code #ifdef'ed since compilers sometimes have trouble removing it.

[SVN r12822]

libs/smart_ptr

@@ -1 +1 @@
-Subproject commit 875bab352c9582f8699591a55cc7c2e479e4ba0c
+Subproject commit 7981b647c31310cbc23d417d752a62ee7986478f