[Bug ada/81878] --disable-bootstrap --enable-languages=ada fails

[tnfchris at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81878

--- Comment #27 from Tamar Christina <tnfchris at gcc dot gnu.org> ---

> Yes, the expected -B flag is present in the screen dump right after -Wl,--stack.
> Are you positive that your change in comment #19 eliminates the problem?

Aaahh Yes, and now I understand what the problem is.. as
https://github.com/Alexpux/MINGW-packages/pull/3877#issuecomment-408660810
points out, gnatlink is a shell script on non-Windows but on Windows it's a
program.  this means it's interpreting the unix paths incorrectly `/home` is
then interpreted by the Windows API. I hadn't understood the comment fully
until now that I knew how it's supposed to work...

The `../..` works because that's a valid path for both.. Not sure why gnatlink
isn't a shell script on Windows too..