autopoint: Unset variables known to interfere with common tools
Reported by Jan Cholasta at:
<https://bugzilla.redhat.com/show_bug.cgi?id=801374>.
* autopoint.in: Unset CDPATH, CLICOLOR_FORCE, and GREP_OPTIONS.
* gettextize.in: Unset CLICOLOR_FORCE and GREP_OPTIONS.
