Ahaggar: no need to check against '\0'

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: check if strtoul() returns 0 for invalid integers

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: check if strtol() and strtoul() returns 0 for invalid int

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>