Reset the variables to NULL after releasing the memory.

This commit was SVN r19912.

ompi/mca/btl/tcp/btl_tcp_component.c

@@ -272,10 +272,15 @@ int mca_btl_tcp_component_close(void)
     opal_list_item_t* item;
     opal_list_item_t* next;
 
-    if(NULL != mca_btl_tcp_component.tcp_if_include)
+    if(NULL != mca_btl_tcp_component.tcp_if_include) {
         free(mca_btl_tcp_component.tcp_if_include);
-    if(NULL != mca_btl_tcp_component.tcp_if_exclude)
+	mca_btl_tcp_component.tcp_if_include = NULL;
+    }
+    if(NULL != mca_btl_tcp_component.tcp_if_exclude) {
        free(mca_btl_tcp_component.tcp_if_exclude);
+       mca_btl_tcp_component.tcp_if_exclude = NULL;
+    }
+
     if (NULL != mca_btl_tcp_component.tcp_btls)
         free(mca_btl_tcp_component.tcp_btls);