c++: Add test [PR95288]

Somewhat improved by r11-2064, though we still generate junk that seems
redundant.  But at least it says
error: expected ‘}’ before ‘.’ token

	PR c++/95288
	* g++.dg/diagnostic/enum2.C: New test.

gcc/testsuite/g++.dg/diagnostic/enum2.C

@@ -0,0 +1,10 @@
+// PR c++/95288
+
+void f()
+{
+  enum X 
+    { // { dg-message "to match this" }
+      a. // { dg-error "expected" }
+      b
+    }; // { dg-error "extra" "" { target c++98_only } }
+} // { dg-error "expected" }