Add missing nsupdate dependency on libirs

Add missing nsupdate dependency on libirs

When commit 8eb88aafee951859264e36c315b1289cd8c2088b removed liblwres,
it also modified nsupdate to use libirs instead of liblwres, but the
Visual Studio project files were not updated to reflect that change.
Make sure the nsupdate Visual Studio project depends on the libirs
project to prevent compilation issues during parallel builds.