selinux: use "grep -E" instead of "egrep"

The latest version of grep claims that egrep is now obsolete so the build
now contains warnings that look like:
	egrep: warning: egrep is obsolescent; using grep -E
fix this by using "grep -E" instead.

Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Cc: Eric Paris <eparis@parisplace.org>
Cc: selinux@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[PM: tweak to remove vdso reference, cleanup subj line]
Signed-off-by: Paul Moore <paul@paul-moore.com>