[Bug libstdc++/71313] [Filesystem TS] remove_all fails to remove directory contents recursively

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71313

--- Comment #3 from Ville Voutilainen <ville.voutilainen at gmail dot com> ---
Fixed on trunk so far, backporting to gcc-6 and gcc-5 shortly.