[Bug libstdc++/88066] Relative includes in bits/locale_conv.h should be prefixed

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88066

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The -I- option is deprecated. Can you use -iquote instead, or are you using
because you want that problematic behaviour?