typo broke the threaded build..

This commit was SVN r7182.

ompi/mca/rcache/rb/rcache_rb_tree.c

@@ -68,7 +68,7 @@ struct mca_rcache_rb_tree_item_t * mca_rcache_rb_tree_find(
         copy = OBJ_NEW(mca_rcache_rb_tree_item_t); 
         *copy = *found; 
     }
-    OPAL_THREAD_UNLOCK(&rb_moduel->rb_lock);
+    OPAL_THREAD_UNLOCK(&rb_module->rb_lock);
     return copy;
 }