[TESTING]: Add a testing program

This can simply be compiled via make pidfd_clone_wait_pidfd and be used to
test the newly added CLONE_WAIT_PIDFD semantics. It tries to verify basic
functionality but also that it plays nicely with ptrace().

Before I sent this patchset I'll add it to kselftests proper.

Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
1 file changed