[Bug libstdc++/85494] implementation of random_device on mingw is useless

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85494

--- Comment #17 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Michel Morin from comment #15)
> I just felt that waiting for GCC-10 (i.e. about a year) is a bit too long.

That's how new features work. If you want to use them, you need the new
version. The time for adding new features to GCC 9 was last year.

Anyway, it should be fixed for mingw-w64 in the gcc-9-branch, so for the GCC
9.2 release.