cpg: Refactor mh_req_exec_cpg_procleave

Most of functionality is moved to do_proc_leave function to make it
reusable.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>
(backport from needle)
cpg: Make sure nodid is always logged as hex num

Also number is prefixed by 0x so it's easier to spot that number is
hexadecimal.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>
(backport from needle)
cpg: Make sure left nodes are really removed

When node is paused and other nodes has in meantime exited cpg process,
paused node after resume doesn't update it's membership correctly so on
previously paused node exited cpg process is still visible.

Solution is to compare join list with cpd and remove all pids which are
not included in join list.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>
(backport from needle)