[Bug libstdc++/95065] Remove std::bind1st and std::bind2nd when building in -std=c++17

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95065

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
For GCC 12 those features will still exist (because as explained above, that is
allowed by the standard) but they will give -Wdeprecated warnings.