Add the ability to specify ptrace rules

ptrace rules currently take the form of

  ptrace [<ptrace_perms>] [<peer_profile_name>],
  ptrace_perm := read|trace|readby|tracedby
  ptrace_perms := ptrace_perm | '(' ptrace_perm+ ')'

After having used the cross check (permission needed in both profiles)
I am not sure it is correct for ptrace.

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>

parser/parser_misc.c

@@ -151,6 +151,9 @@ static struct keyword_table keyword_table[] = {
 	{"write",               TOK_WRITE},
 	{"eavesdrop",		TOK_EAVESDROP},
 	{"peer",		TOK_PEER},
+	{"trace",		TOK_TRACE},
+	{"tracedby",		TOK_TRACEDBY},
+	{"readby",		TOK_READBY},
 
 	/* terminate */
 	{NULL, 0}