Trivial cleanup.  do_execve_common() can use current_user() and avoid the
unnecessary "struct cred *cred" var.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>