gplazma2-xacml: fix regression on network address sort

module:  gplazma2-xacml

svn trunk@18137 altered NetworkUtils to use an immutable list for local addresses.  The XACML plugin needs to sort these according to external/internal.  This sort was failing and causing failure to load the plugin (undiscovered until now).

Patch copies the immutable list and then sorts.

Target: 2.6
Patch: http://rb.dcache.org/r/5539
Require-notes: no
Require-book: no
Acked-by: Paul