3-argument form of DATE_FORMAT

Implement Field_timestamp::save_in_field(timestamp_field)
that stores timestamp values without converting them to MYSQL_TIME
and back, because this conversion is lossy around DST change time.
This fixes main.old-mode test.

This is 10.2 version of f8a800be

Implement a special Copy_func function for timestamps, that copies
timestamps without converting them to MYSQL_TIME (the conversion is
lossy around DST change time).

This fixes ALTER TABLE part of main.old-mode test.

This is 10.2 version of f4f48e06

make insert NULL into a timestamp mark the field as having an
explicit value. So that the field won't be assigned the value
again in TABLE::update_default_field()

make Item_func_now_local::save_in_field(timestamp_field) not to go
through MYSQL_TIME - this conversion is lossy around DST change times.
This fixes inserting a default value into a timestamp field.

This is a preparatory step for MDEV-13864.
It does not change behavior in any ways. It simply splits methods into smaller peaces.
The intent of this separate patch is to make more readable the main patch for
MDEV-13864 (which will actually move the predicant to args[0]).

1. Splitting fix_length_and_dec() into smaller pieces, adding:
  - bool aggregate_then_and_else_arguments(THD *thd);
  - bool aggregate_switch_and_when_arguments(THD *thd);

2. Splitting find_item() into smaller pieces, adding:
  - Item *find_item_searched();
  - Item *find_item_simple();

3. Splitting print() into smaller pieces, adding:

  - void print_when_then_arguments(String *str, enum_query_type query_type,
                                   Item **items, uint count);
  - void print_else_argument(String *str, enum_query_type query_type, Item *item)

4. Moving the maybe_null handling part related to ELSE from fix_length_and_dec()
   to fix_fields(), as in all other Item_func's.

5. Removing the unused String* argument from find_item().

6. Moving find_item() from public to private, as it's not needed outside.

But without f4f48e06..f8a800be - fixes for MDEV-12672
and related issues. 10.2 specific fix follows...

don't do it via MYSQL_TIME, that conversion is lossy
around DST change dates.

Implement a special Copy_field method for timestamps, that copies
timestamps without converting them to MYSQL_TIME (the conversion
is lossy around DST change dates).

libmariadbclient_18 version nodes, specially for debian builds

followup for 378beed0 - only count WARN_LEVEL_ERROR,
not warnings or notes.

tabtyp was defined under ODBC_SUPPORT, but used
outside of it too (under JDBC_SUPPORT).

Even if cmake can find pkg-config (e.g the one supplied with strawberry perl
), we cannot link with pkg-config-found libraries or use the headers -they
are mingw, 32bit-only.

- Added missing test case for MyISAM

Fix description of version_source_revision

Node pointer recors contain dict_index_get_n_unique_in_tree_nonleaf(index)+1
instead of index->n_uniq+1 fields.

rec_get_offsets_func(): Remove the incorrect assertion. Later in
the function there are assertion for checking the exact field count.

Added version_source_revision server "variable", for the git revision.
Also , mysql -V will show git revision.

"make dist" will now pack source_revision.h into the source package.

don't prepare for checking view's CHECK OPTION, if
there is no CHECK OPTION in the first place.

Binlog_background_thread does not make a call to set_time(), And when
we call binlog_checkpoint_log_event->write() , we write the wrong timestamp.
In this patch we correct this by calling thd->set_time().

When the debug parameter 'bool leaf' was added to rec_get_offsets(),
also some debug assertions for reading the heap_no of ROW_FORMAT=REDUNDANT
records were added. However, the heap number is uninitialized when
offsets are being computed for to-be-inserted records.

For debug builds, initialize the heap number to a dummy value, so that
the record will be interpreted as 'user record'. The infimum and supremum
pseudo-records are never copied from the page frame and never inserted;
they are part of the page creation.

rec_convert_dtuple_to_rec_old(): Remove a bogus memset() in debug builds.

Problem:- To create file in /tmp dir mysqld require permission initrc_tmp_t.
And mysqld does not have his permission.

Solution:- Instead of giving mysqld permission of initrc_tmp_t , we redirected
log to file in /tmp dir through shell. I also removed a earlier workarround
in mysqld_safe.sh , which create tmp log file in datadir.

followup for b5ead3a6

libmariadb3 does not replace 10.1's libmariadbclient18 anymore,
but it still conflicts with it, both install dialog.so

This fixes a regression that only affects debug builds, caused by
commit 48192f96 which is necessary
preparation for MDEV-11369 instant ADD COLUMN. (Although that is a
10.3 task, to ease merges between 10.2 and 10.3, this change that
improves debug checks was pushed to 10.2 already.)

Unlike btr_pcur_restore_position(), rtr_cur_restore_position()
can create a search tuple out of a non-leaf page record. So,
we must pass 'bool leaf' parameter to dict_index_build_data_tuple().

dict_index_build_data_tuple(): Add a debug-only parameter 'bool leaf'.

rec_copy_prefix_to_dtuple(): Make the parameter debug-only.

row_sel_get_clust_rec_for_mysql(): In the debug code for spatial index,
remove an unnecessary call to buf_page_get_gen(), and use the already
latched block directly.