Release temporary array in check_for_data_types_usage().

Coverity identified this as a resource leak.  It's surely of no
consequence given that the function is called only once per run, but
freeing the storage is no more work than dismissing the complaint.
Minor oversight in commit 347758b12.

src/bin/pg_upgrade/check.c

@@ -521,6 +521,8 @@ check_for_data_types_usage(ClusterInfo *cluster, DataTypesUsageChecks * checks)
 	if (found)
 		pg_fatal("Data type checks failed: %s", report.data);
 
+	pg_free(results);
+
 	check_ok();
 }