On Hurd, do not look for functions unimplemented in libc

On Hurd, do not look for functions unimplemented in libc

Last-Update: 2022-02-22
Forwarded: not-needed

The check_function_exists() function of cmake does not keep into account the
defines that glibc provides for the stubs (i.e. unimplemented functions that
always return ENOSYS), so some functions are detected as available.
Unfortunately, due to --fatal-warnings for the linker, linking will fail.
Hence, do not attempt to look for functions that are currently unimplemented
on GNU/Hurd's libc.

Gbp-Pq: Name hurd_disable_unimplemented.diff