procfs: add seq_put_hex_ll to speed up /proc/pid/maps [avagin@openvz.org: use unsigned int instead of int... ...kernel.org/r/20180214025619.4005-1-avagin@openvz.org [avagin@openvz.org: v2] ...kernel.org/r/20180117082050.25406-1-avagin@openvz.org ...kernel.org/r/20180112185812.7710-1-avagin@openvz.org Signed-off-by: Andrei Vagin <avagin@openvz.org>