userns: Convert ptrace, kill, set_priority permission checks to work with kuids and...

Update the permission checks to use the new uid_eq and gid_eq helpers
and remove the now unnecessary user_ns equality comparison.

Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

diff --cc kernel/ptrace.c
Simple merge

diff --cc kernel/signal.c
Simple merge

diff --cc kernel/sys.c
Simple merge