SELinux: portage_ro_role

Hello,

our portage policy includes a portage_ro_role interface to allow
read-only access to portage data. As usual with _role interfaces,
according to the documentation the interface takes a role as the first
($1) and a type as the second argument ($2). However, the directives
in the interface actually expect $1 to be a type.

So, we should either
1) replace $1 with $2 inside the interface, or
2) rename the interface to something without _role and fix the
   documentation.

Regards,
Luis Ressel