Add an XXX: linux_uselib() should be using vn_open() rather than invoking

VOP_OPEN() and doing lots of manual checking.  This would further
centralize use of the name functions, and once the MAC code is integrated,
meaning few extraneous MAC checks scattered all over the place.  I don't
have time to fix this now, but want to make sure it doesn't get
forgotten.  Anyone interested in fixing this should feel free.

Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, NAI Labs

sys/compat/linux/linux_misc.c

@@ -255,6 +255,10 @@ linux_uselib(struct thread *td, struct linux_uselib_args *args)
 	locked = 0;
 	vp = NULL;
 
+	/*
+	 * XXX This code should make use of vn_open(), rather than doing
+	 * all this stuff itself.
+	 */
 	NDINIT(&ni, LOOKUP, FOLLOW|LOCKLEAF, UIO_USERSPACE, args->library, td);
 	error = namei(&ni);
 	if (error)