Fix previous commit.

From-SVN: r163442

gcc/testsuite/g++.dg/tree-ssa/empty-2.C

 // PR c++/45307
-// { dg-options "-fdump-tree-gimple -fdump-tree-optimized" }
+// { dg-options "-fdump-tree-gimple -fdump-tree-optimized -O" }
 
 struct fallible_t { };
 const fallible_t fallible = fallible_t();
 
+void t(void)
+{
+}
+
 // { dg-final { scan-tree-dump-not "fallible" "gimple" } }
 // Whole constructor should be optimized away.
 // { dg-final { scan-tree-dump-not "int" "optimized" } }