Fix two missing DBUG_RETURN.

libmysql/libmysql.c

@@ -4634,7 +4634,7 @@ int STDCALL mysql_stmt_fetch_column(MYSQL_STMT *stmt, MYSQL_BIND *my_bind,
   if ((int) stmt->state < (int) MYSQL_STMT_FETCH_DONE)
   {
     set_stmt_error(stmt, CR_NO_DATA, unknown_sqlstate, NULL);
-    return 1;
+    DBUG_RETURN(1);
   }
   if (column >= stmt->field_count)
   {

tests/mysql_client_test.c

@@ -16295,6 +16295,8 @@ static void test_bug27876()
 
   rc= mysql_query(mysql, "set names default");
   myquery(rc);
+
+  DBUG_VOID_RETURN;
 }