fix warning

[r17214]

ir/ir/irnode.c

@@ -41,6 +41,7 @@
 #include "irprog_t.h"
 #include "iredgekinds.h"
 #include "iredges_t.h"
+#include "ircons.h"
 
 #include "irhooks.h"
 #include "irtools.h"
@@ -883,7 +884,7 @@ ir_node *get_irn_MacroBlock(const ir_node *n) {
 		n = get_nodes_block(n);
 		/* if the Block is Bad, do NOT try to get it's MB, it will fail. */
 		if (is_Bad(n))
-			return n;
+			return new_Bad();
 	}
 	return get_Block_MacroBlock(n);
 }