userns: Convert process event connector to handle kuids and kgids

- Only allow asking for events from the initial user and pid namespace,
  where we generate the events in.

- Convert kuids and kgids into the initial user namespace to report
  them via the process event connector.

Cc: David Miller <davem@davemloft.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

init/Kconfig

@@ -938,7 +938,6 @@ config UIDGID_CONVERTED
 	depends on QUOTACTL = n
 	depends on BSD_PROCESS_ACCT = n
 	depends on DRM = n
-	depends on PROC_EVENTS = n
 
 	# Networking
 	depends on NET_9P = n