[Bug libstdc++/82366] std::regex constructor called from shared library throws std::bad_cast

[spamdrop at fodvo dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82366

--- Comment #4 from spamdrop at fodvo dot org ---
One more comment to add before I forget, If I change the regex string to remove
the []'s, while the program doesn't do the correct thing (obviously), it at
least doesn't throw the exception.  Not sure if that has any significant
meaning.