[Bug libstdc++/67537] [6 Regression] r225189 breaks building boost hana

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67537

--- Comment #4 from Ville Voutilainen <ville.voutilainen at gmail dot com> ---
I'll see if I can do a reasonable library fix, even if the problem is
caused by a buggy front-end.