Fix the conversion macro for .note sections, broken in the case
the ELF file's byte order is not the native byte order.  The
bug is that the variables holding the name and description size
are used (natively) after having been byte-swapped.  The fix is
to calculate sz from them just prior to byte-swapping.

Approved by:	jkoshy@
Obtained from:	Juniper Networks, Inc.
Avoid crdup when possible in kern_accessat.

While here tidy up a little.