[apparmor] Changing the link pair rule

[John Johansen]

I would like to propose that we change the syntax of the link pair rule
slightly.  Currently it takes the form of

  link [subset] <link> -> <target>,

I would like to remove the use of -> and change it for "to" or something
else.  The reason is that I would like to keep -> dedicated for profile
transitions.  I don't know of anyone currently using the link rule
in the pair form so now seems like the time to change it.