Move negate' translate_state() to utils_base.h

Also changed to strcasecmp, may need additions from gnulib. - Thanks dermoth (https://github.com/monitoring-plugins/monitoring-plugins/commit/8fc9e5ac4b3a699f8d6b78471829692f0c92d5fa)
Update check_swap usage

Update and clarify check_swap usage. - Thanks dermoth (https://github.com/monitoring-plugins/monitoring-plugins/commit/813c02364f55c14fef396d83eed52874d8e16fb2)