security: drop meta-security

meta-security previously had implicit dependencies on meta-openembedded's
meta-oe and meta-perl, but I could work around them.  Now they're explicit
and so I'll create a separate repo project for all of meta-security and
keep meta-selinux as small as possible.

Change-Id: Ibb314850cad88d4ca84c838ecea18baaaa082002
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>