Link against libselinux

The library provides an implementation for setfilecon().

Signed-off-by: Alberto Faria <afaria@redhat.com>

build.rs

@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+fn main() {
+    println!("cargo:rustc-link-lib=selinux");
+}