libapparmor: build perl bindings

There are still a few utils which use Perl, though most have been ported to
Python. Note that SWIG v2 is required to avoid the `error: 'bool' undeclared`
build failure with Perl >=5.16 [1].

[1]: 4305a3cef9

pkgs/os-specific/linux/apparmor/2.9/default.nix

@@ -54,7 +54,7 @@ let
     buildPhase = ''
       cd ./libraries/libapparmor
       ./autogen.sh
-      ./configure --prefix="$out" --with-python
+      ./configure --prefix="$out" --with-python --with-perl
       make
       '';