casts, etc

real changes are:
* remove one retry, it is enough to check for DELETED
  after the key is read
* advance 'head' pointer when we see a dummy node to have
  shorter retries

Add fix for MDEV-7369

See also https://mariadb.atlassian.net/browse/MDEV-7369

log-tc-size is 24K by default. Page size is 64K on PPC64. But log-tc-size
must be at least 3 x page size. This is enforced by TC_LOG_MMAP::open()
with a comment: to guarantee non-empty pool.

This all makes server not startable in default configuration on PPC64.

Autosize log-tc-size, so that it's min value= page size * 3, default
value= page size * 6, block size= page size.

wsrep_status was renamed to wsrep_info. Adjusted deb build scripts accordingly.

getopt value pointer of "debug" variable was pointing to incorrect address:
&global_system_variables. Runtime statements like SHOW VARIABLES materialize
value from DBUG structures on demand, so they never access getopt value pointer.
But mysqld --help --verbose loaded this value from &global_system_variables.

Remove "debug" variable from mysqld --help --verbose output by setting value
pointer to NULL.

        The srid variable was used uninitialised when the field wasn't GIS.
        Only problem is that it makes the debugger unhappy. Still added
        the initialization.

Addendum : Renamed plugin .so file.

Implement --semi-sync-master-wait-point=AFTER_SYNC|AFTER_COMMIT.

When AFTER_SYNC, the semi-sync wait will be done earlier, before the storage
engine commit rather than after. This means that a transaction will not be
visible on the master until at least one slave has received it.

Make the binlog dump threads not need to take LOCK_log while sending
binlog events to slave. Instead, a new LOCK_binlog_end_pos is used
just to coordinate tracking the current end-of-log.

This is a pre-requisite for MDEV-162, "Enhanced semisync
replication". It should also help reduce the contention on LOCK_log on
a busy master.

Also does some much-needed refactoring/cleanup of the related code in
the binlog dump thread.

Adding "--source include/have_udf.inc" and a few "--replace" commands.

MDEV-7282 SP: CREATE OR REPLACE, CREATE IF NOT EXISTS

where the former is enough.

An additional debug test, made by Sriram Patil while working on
"CREATE VIEW IF NOT EXISTS".

Forgot to do "git add" for a number of files in the previous commit.

A clean-up: require CREATE+DROP privileges for "CREATE OR REPLACE DATABASE",
instead of just CREATE privilege.

A test clean-up: The "SHOW DATABASES" queries now use "LIKE 'db%'",
to display only the databases created during this test,
thus exclude the system databases, as some of them can be optional
(e.g. performance_schema).

- Single_line_formatting_helper should not accidentally exit the
  DISABLED state. No JSON construct should be able to move the
  Single_line_formatting_helper from DISABLED state.

Implement a new mode for parallel replication. In this mode, all transactions
are optimistically attempted applied in parallel. In case of conflicts, the
offending transaction is rolled back and retried later non-parallel.

This is an early-release patch to facilitate testing, more changes to user
interface / options will be expected. The new mode is not enabled by default.

Switch EXPLAIN JSON from using subselect_engine::get_identifier()
to the number from Item_subselect::unit.

Remove subselect_union_engine::get_identifier() because it was added
only for EXPLAIN JSON code.

Join_plan_state performs out-of-API initialization of DYNAMIC_ARRAY. This is
done to postpone actual array initialization till first use, whilst retaining
the right to call delete_dynamic().

Since delete_dynamic() now checks DYNAMIC_ARRAY::malloc_flags it should be
initialized it as well.

- Changed 0x%lx -> %p
array.c:
- Static (preallocated) buffer can now be anywhere
my_sys.h
- Define MY_INIT_BUFFER_USED
sql_delete.cc & sql_lex.cc
- Use memroot when allocating classes (avoids call to current_thd)
sql_explain.h:
- Use preallocated buffers
sql_explain.cc:
- Use preallocated buffers and memroot
sql_select.cc:
- Use multi_alloc_root() instead of many alloc_root()
- Update calls to Explain

Preallocate dynamic array and bitmap on mem_root to avoid expensive malloc.
This reduces number of allocations from 39 to 31 per OLTP RO transaction.

Preallocate dynamic array on THD mem_root to avoid expensive malloc.

so that a simple query with one join would not have to call my_malloc.
- Allow lower limites for query_prealloc_size for testing.
- Fixed wrong initialization of trans_alloc_block_size