Conflicts:
	sql/sp_rcontext.cc

current_select may point to data from old parser states
when calling a stored procedure with CALL

The failure happens in Item::Item when testing if we are
in having.

Fixed by explicitely reseting current_select in do_execute_sp()
and in sp_rcontext::create(). The later is also needed for
stored functions().

caused an error

The function subselect_single_select_engine::print() did not print
the WITH clause attached to a subselect with single select engine.
As a result views using suqueries with attached WITH clauses lost
these clauses when saved in frm files.

The field trx_rseg_t::trx_ref_count that was added in WL#6965 in
MySQL 5.7.5 is being incremented twice if a recovered transaction
includes both undo log partitions insert_undo and update_undo.

This reference count is being used in trx_purge(), which invokes
trx_purge_initiate_truncate() to try to truncate an undo tablespace
file. Because of the double-increment, the trx_ref_count would never
reach 0.

It is possible that after the failed truncation attempt, the undo
tablespace would be disabled for logging any new transactions until
the server is restarted (hopefully after committing or rolling back
all transactions, so that no transactions would be recovered
on the next startup).

trx_resurrect_insert(), trx_resurrect_update(): Do not increment
trx_ref_count. Instead, let the caller do that.

trx_lists_init_at_db_start(): Increment rseg->trx_ref_count only
once for each recovered transaction. Adjust comments.
Finally, if innodb_force_recovery prevents the undo log scan,
do not bother iterating the empty lists.

The problem was that max_size was acciently set to 1 in some
cases.

Other things:
- Adjust max_rows if min_rows > max_rows.
- Removed not used variable varchar_length
- Adjusted max_pack_length (safety fix)

If InnoDB is killed while ALTER TABLE...ALGORITHM=COPY is in progress,
after recovery there could be undo log records some records that were
inserted into an intermediate copy of the table. Due to these undo log
records, InnoDB would resurrect locks at recovery, and the intermediate
table would be locked while we are trying to drop it. This would cause
a call to row_rename_table_for_mysql(), either from
row_mysql_drop_garbage_tables() or from the rollback of a RENAME
operation that was part of the ALTER TABLE.

row_rename_table_for_mysql(): Do not attempt to parse FOREIGN KEY
constraints when renaming from #sql-something to #sql-something-else,
because it does not make any sense.

row_drop_table_for_mysql(): When deferring DROP TABLE due to locks,
do not rename the table if its name already starts with the #sql-
prefix, which is what row_mysql_drop_garbage_tables() uses.
Previously, the too strict prefix #sql-ib was used, and some
tables were renamed unnecessarily.

Follow-up to commit 9ec19b9b

srv_prepare_to_delete_redo_log_files(): Initialize srv_start_lsn.

1. Moving the following methods from THD to Item_change_list:
   nocheck_register_item_tree_change()
   check_and_register_item_tree_change()
   rollback_item_tree_changes()
   as they work only with the "change_list" member and don't
   require anything else from THD.
2. Deriving THD from Item_change_list

This change will help to fix "MDEV-14603 signal 11 with short stacktrace" easier.

innobase_start_or_create_for_mysql(): Only start the data dictionary
and transaction subsystems in normal server startup and during
mariabackup --export.

btr_cur_update_in_place(): Read block->index only once,
so that it cannot change to NULL after the first read.
When block->index != NULL, it must be equal to index.

btr_cur_update_in_place(): The call rw_lock_x_lock(ahi_latch) must
of course be inside the if (ahi_latch) condition. This is a mistake
that I made when backporting the fix-under-development from 10.3.

This race condition is a regression caused by MDEV-12121.

btr_cur_update_in_place(): Determine block->index!=NULL only once
in order to determine whether an adaptive hash index bucket needs
to be exclusively locked and unlocked.

If we evaluated block->index multiple times, and the adaptive hash
index was disabled before we locked the adaptive hash index, then
we would never release the adaptive hash index bucket latch, which
would eventually lead to InnoDB hanging.

innodb.truncate_inject: Replacement for innodb_zip.wl6501_error_1

Note: unlike MySQL, in some cases TRUNCATE does not return
an error in MariaDB. This should be fixed in the scope of
MDEV-13564 or similar.

Speed up compilation

Standard C++ headers contribute a lot to compilation time. Avoid algorithm
and sstream in frequently used headers.

commit 3dc3ab1a introduced
Rows_event_tracker, using a mismatch of size_t (the native
register width) and my_off_t (the file offset width, usually
64 bits). Use my_off_t both in member fields and member functions.

This is a regression that was introduced in MySQL 5.7.6 in
https://github.com/mysql/mysql-server/commit/19855664de0245ff24e0753dc82723fc4e2fb7a5

fil_node_open_file(): Use proper 64-bit arithmetics for truncating
size_bytes to a multiple of a file extent size.

- Removed extra set -x -v used for debugging
- Fixed that that gcc version tests works for gcc 7

Server already has HMT_low/HMT_medium.

- Make Rdb_binlog_manager::unpack_value to not have a stack overrun
  when it is reading invalid data (which it currently does as we in
  MariaDB do not store binlog coordinates under BINLOG_INFO_INDEX_NUMBER,
  see comments in MDEV-14892 for details).
- We may need to store these coordinates in the future, so instead of
  removing the call of this function, let's make it work properly for
  all possible inputs.

Problems --------

The slave io thread did not conduct integrity check
for a group of row-based events. Specifically it tolerates missed
terminal block event that must be flagged with STMT_END. Failure to
react on its loss can confuse the applier thread in various ways.
Another potential issue was that there were no check of impossible
second in row Gtid-log-event while the slave io thread is receiving
to be skipped events after reconnect.

Fixes
-----
The slave io thread is made by this patch to track the rows event
STMT_END status.
Whenever at next event reading the IO thread finds out that a preceding
Rows event did not actually had the flag, an
explicit error is issued.

Replication can be resumed after the source of failure is eliminated,
see a provided test.

Note that currently the row-based group integrity check excludes
the compressed version 2 Rows events (which are not generated by MariaDB
master).
Its uncompressed counterpart is manually tested.

The 2nd issue is covered to produce an error in case the io thread
receives a successive Gtid_log_event while it is post-reconnect
skipping.