Need this variable in optimized builds, too.

This commit was SVN r23937.

opal/mca/event/libevent207/libevent207_module.c

@@ -155,9 +155,7 @@ static const struct eventop *eventops[] = {
 	NULL
 };
 
-#if OPAL_ENABLE_DEBUG
 static int debug_output = -1;
-#endif
 
 static void constructor(opal_event_t *ev)
 {