Includes fix for Bug #38180, "options are read from ~/my.cnf instead of ~/.my.cnf"

Includes fix for Bug #38180, "options are read from ~/my.cnf instead of ~/.my.cnf"

Pull out some of unpack_dirname() into normalize_dirname(); this
new function does not expand "~" to the home directory.  Use this
function in unpack_dirname(), and use it during init_default_directories()
to remove duplicate entries without losing track of which directory
is a user's home dir.

offset for time part in UUIDs was 1/1000 of what it
should be. In other words, offset was off.

Also handle the case where we count into the future
when several UUIDs are generated in one "tick", and
then the next call is late enough for us to unwind
some but not all of those borrowed ticks.

Lastly, handle the case where we keep borrowing and
borrowing until the tick-counter overflows by also
changing into a new "numberspace" by creating a new
random suffix.

offset for time part in UUIDs was 1/1000 of what it
should be. In other words, offset was off.

Also handle the case where we count into the future
when several UUIDs are generated in one "tick", and
then the next call is late enough for us to unwind
some but not all of those borrowed ticks.

Lastly, handle the case where we keep borrowing and
borrowing until the tick-counter overflows by also
changing into a new "numberspace" by creating a new
random suffix.

   "funcs_2: The tests do not check if optional character
               sets exist."
2. Minor cleanup

The problem is that relying on the output of the 'ls' command is not
portable as its behavior is not the same between systems and it might
even not be available at all in (Windows).

So I added list_files that relies on the portable mysys library instead.
(and also list_files_write_file and list_files_append_file,
since the test was using '--exec ls' in that way.)

Fixed the test to expect the correct result.
The previous test script was in fact affected by 26030,
and wrongly expected a ER_PARSE_ERROR error.

problem was that ha_partition::records was not implemented, thus
using the default handler::records, which is not correct if the engine
does not support HA_STATS_RECORDS_IS_EXACT.
Solution was to implement ha_partition::records as a wrapper around
the underlying partitions records.

The rows column in explain partitions will now include the total
number of records in the partitioned table.

(recommit after removing out-commented code)

enabled)

Before this fix, the lexer and parser would treat the ';' character as a
different token (either ';' or END_OF_INPUT), based on convoluted logic,
which failed in simple cases where a stored procedure is implemented as a
single statement, and used in a multi query.

With this fix:
- the character ';' is always parsed as a ';' token in the lexer,
- parsing multi queries is implemented in the parser, in the 'query:' rules,
- the value of thd->client_capabilities, which is the capabilities
  negotiated between the client and the server during bootstrap,
  is immutable and not arbitrarily modified during parsing (which was the
  root cause of the bug)

 - moved the test into a separate file to check for presence of the test variable

On certain kinds of errors (e.g., out of stack), a call to Item_func_
set_user_var::fix_fields() might fail.  Since the return value of this
call was not checked inside User_var_log_event::exec_event(), continuing
execution after this will cause a crash inside Item_func_set_user_var::
update_hash().

The bug is fixed by aborting execution of the event with an error if
fix_fields() fails, since it is not possible to continue execution anyway.