[Bug libstdc++/79820] std::ifstream sets errno to zero

[i.nixman at autistici dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79820

--- Comment #6 from niXman <i.nixman at autistici dot org> ---
Created attachment 40970
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40970&action=edit
patch

done.