Fixed missing diagnosis on function parameter lists with trailing commas.

test/err/bug2301-trailing-coma-1.c

@@ -0,0 +1,3 @@
+/* Bug #2301 - Function parameter list with an extra trailing comma should not compile */
+
+int foo(int a,); /* Should fail */

test/err/bug2301-trailing-coma-2.c

@@ -0,0 +1,6 @@
+/* Bug #2301 - Function parameter list with an extra trailing comma should not compile */
+
+int bar(a,) int a;  /* Should fail */
+{
+    return a;
+}