https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111141
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I think we should improve the toplevel configure to error out if including
errno.h fails.
So instead of:
```
echo "int main () { return 0; }" > conftest.c
```
We should do:
```
echo "#include <errno.h>" > conftest.c
echo "int main () { return 0; }" >> conftest.c
```
I don't have a way to test this but this should at least cause the failure to
happen earlier during configure rather than later on.
