improve error message for functions that require an absoulte path, see:
 * https://dev.cfengine.com/issues/6877
(cherry picked from commit 3f72cb51ee96d3b63c391f110592f0dd83d1ec6a)
fixed spelling error in ABSOLUTE and remove double strcmp test
(cherry picked from commit 14f4136a40b23cb2c4d10f32a3b11ef558fac475)