sys-apps/systemd-tmpfiles: Add selinux USE flag.

Previously systemd-tmpfiles was always compiled without selinux
support.

Upstream bug: https://bugs.gentoo.org/757810

BUG=chromium:884826
TEST=ls -ldZ /run/dbus

Change-Id: Ia3528404d4604bbea00ffc8d476270c3e377b307
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2565759
Tested-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Allen Webb <allenwebb@google.com>
diff --git a/sys-apps/systemd-tmpfiles/systemd-tmpfiles-246.ebuild b/sys-apps/systemd-tmpfiles/systemd-tmpfiles-246-r1.ebuild
similarity index 97%
rename from sys-apps/systemd-tmpfiles/systemd-tmpfiles-246.ebuild
rename to sys-apps/systemd-tmpfiles/systemd-tmpfiles-246-r1.ebuild
index 6898ebf..24865d5 100644
--- a/sys-apps/systemd-tmpfiles/systemd-tmpfiles-246.ebuild
+++ b/sys-apps/systemd-tmpfiles/systemd-tmpfiles-246-r1.ebuild
@@ -15,7 +15,7 @@
 LICENSE="BSD-2 GPL-2 LGPL-2.1 MIT public-domain"
 SLOT="0"
 KEYWORDS="*"
-IUSE="test"
+IUSE="selinux test"
 RESTRICT="!test? ( test )"
 
 DEPEND="
@@ -23,6 +23,7 @@
 	>=sys-apps/util-linux-2.30:0=
 	>=sys-kernel/linux-headers-${MINKV}
 	sys-libs/libcap:0=
+	selinux? ( sys-libs/libselinux:0= )
 "
 RDEPEND="${DEPEND}
 	!sys-apps/opentmpfiles
@@ -117,7 +118,7 @@
 		resolve
 		rfkill
 		seccomp
-		selinux
+		$(usex selinux '' selinux)
 		smack
 		sysusers
 		timedated