[Bug bootstrap/78616] [7 regression] bootstrap fails for x86_64-darwin at stage1 after 243030 when the bootstrap compiler doesn't have strndup

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78616

--- Comment #1 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
If I'm reading things right, it looks like libiberty provides an implementation
of strndup if it's not available, but it doesn't provide a decl for it.