[Bug libstdc++/89816] [9 Regression] std::variant move construction regressed since GCC 8.3

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89816

--- Comment #7 from Ville Voutilainen <ville.voutilainen at gmail dot com> ---
Looks good - I'll do a patch shortly.