COMP: Fix building of Slicer on MacOSX when cronjob is used

Extending PATH with /usr/sbin will allow the OpenSSL config script to
properly find 'sysctl' executable so that the configuration succeed.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22374 3bd1e089-480b-0410-8dfb-8563597acbee