SHOW MAXIMUM NUMBER OF OPEN FILES

The read-only system variable open_files_limit did not
show maximum number of open files the mysqld process
could have, but instead the number that was requested
after adjusting the start-up option open_files_limit.

Fixed by adding internal variable for propagating
the requested number of files, since that was used
for adjusting other start-up options. And set
the read-only system variable open_files_limit
to the real maximum value.