PR# 14472 System that creates one trivial thread at a time leaks memory

A system repeatedly creates one worker thread, where the worker thread `execute'
routine does not do anything, and then calls join_all to wait for that thread.
When the system is executed with a large number of iterations, it runs out of
memory, though MEM_INFO shows stable memory usage.

I believe part (perhaps all) of the problem is that `ex_string' is allocated
by `init_emnger' in except.c (per thread data), but is never freed when the
thread terminates.

Finalize with attached classes and config file.
Execute system with argument 100000.  On my system, memory usage for the process
grows to about 800 MB before execution finishes, though MEM_INFO shows
total memory usage as 16785600 bytes.

The memory leak has been fixed in rev#73858.
Thank you for reporting.

Attachments for problem report #14472