makeArrayTypeName: Remove pointless relation open/close

Discussion: https://postgr.es/m/20191218221326.GA25537@alvherre.pgsql

src/backend/catalog/pg_type.c

@@ -785,15 +785,12 @@ makeArrayTypeName(const char *typeName, Oid typeNamespace)
 {
 	char	   *arr = (char *) palloc(NAMEDATALEN);
 	int			namelen = strlen(typeName);
-	Relation	pg_type_desc;
 	int			i;
 
 	/*
 	 * The idea is to prepend underscores as needed until we make a name that
 	 * doesn't collide with anything...
 	 */
-	pg_type_desc = table_open(TypeRelationId, AccessShareLock);
-
 	for (i = 1; i < NAMEDATALEN - 1; i++)
 	{
 		arr[i - 1] = '_';
@@ -810,8 +807,6 @@ makeArrayTypeName(const char *typeName, Oid typeNamespace)
 			break;
 	}
 
-	table_close(pg_type_desc, AccessShareLock);
-
 	if (i >= NAMEDATALEN - 1)
 		ereport(ERROR,
 				(errcode(ERRCODE_DUPLICATE_OBJECT),