MXS-1380 Parse UNIONs completely

Before this change, only db2.t2 was reported as table name for a
select like

    select * from db1.t1 union select * from db2.t2

With this change, db1.t1 and db2.t2 are reported.

query_classifier/test/insert.test

@@ -523,7 +523,9 @@ insert t1 (data) values ('letter'), (1/0);
 --disable_ps_protocol
 update t1 set data='envelope' where 1/0 or 1;
 --enable_ps_protocol
-insert t1 (data) values (default), (1/0), ('dead beef');
+#MXS qc_mysqlembedded does not return all functions
+#MXS qc_get_function_info     : ERR:  != /()
+#MXS insert t1 (data) values (default), (1/0), ('dead beef');
 --disable_info
 
 set sql_mode=default;

query_classifier/test/maxscale.test

@@ -79,3 +79,5 @@ ROLLBACK TO id;
 RELEASE SAVEPOINT id;
 
 SELECT her FROM (SELECT @@server_id as her) as t WHERE her REGEXP '.*';
+
+select * from db1.t1 union select * from db2.t2

query_classifier/test/select.test

@@ -3296,10 +3296,12 @@ DROP TABLE t1,t2;
 #
 
 create table t1 (a bigint unsigned);
-insert into t1 values
-  (if(1, 9223372036854775808, 1)),
-  (case when 1 then 9223372036854775808 else 1 end),
-  (coalesce(9223372036854775808, 1));
+#MXS qc_mysqlembedded does not return all functions
+#MXS qc_get_function_info     : ERR: coalesce() != case() coalesce() if()
+#insert into t1 values
+#  (if(1, 9223372036854775808, 1)),
+#  (case when 1 then 9223372036854775808 else 1 end),
+#  (coalesce(9223372036854775808, 1));
 select * from t1;
 drop table t1;
 create table t1 select