[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[kariya_mitsuru at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #3 from Mitsuru Kariya <kariya_mitsuru at hotmail dot com> ---
Sorry, I confused the copy ctor with the copy assignment operator.
But it seems that both are same results.

operator= version : http://melpon.org/wandbox/permlink/ZHzYukOyuluuzpwu

I didn't notice, but both the copy ctor and the copy assignment operator of
match_results are also same results as Mr. Wakely pointed out above.

copy ctor version : http://melpon.org/wandbox/permlink/Z4Z0kr5yTcB0iyEk
operator= version : http://melpon.org/wandbox/permlink/tHBSWP3hJpinggzw