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)