add missing test for "typedef auto"

From-SVN: r117642

gcc/testsuite/g++.dg/parse/typedef8.C

@@ -4,3 +4,8 @@ typedef static int a;   // { dg-error "conflicting" }
 typedef register int b; // { dg-error "conflicting" }
 typedef extern int c;   // { dg-error "conflicting" }
 static typedef int a;   // { dg-error "conflicting" }
+
+int foo()
+{
+  typedef auto int bar; // { dg-error "conflicting" }
+}