Avoid installing security.functions with executable bits, periodic(8) will
try to execute all files with an executable bit in /etc/periodic/*/ while
this file is supposed only to be sourced by others

MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@274130 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f