This commit implements the standard SQL extension
OFFSET start { ROW | ROWS }
[FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } { ONLY | WITH TIES }]
To achieve this a reserved keyword OFFSET is introduced.
The general logic for WITH TIES implies:
1. The number of rows a query returns is no longer known during optimize
phase. Adjust optimizations to no longer consider this.
2. During end_send make use of an "order Cached_item"to compare if the
ORDER BY columns changed. Keep returning rows until there is a
change. This happens only after we reached the row limit.
3. Within end_send_group, the order by clause was eliminated. It is
still possible to keep the optimization of using end_send_group for
producing the final result set.
fix mysql_fix_privilege_tables to look for the `user` table in the
correct schema when deciding whether to convert it to `global_priv` table
make related tests a bit more verbose
