new option "buildxs" for Perl modules

Hi,

I would like to introduce an option

  buildxs       build Perl XS module(s)

for Perl modules. Although I can come up with only one example (Net-DNS)
at the moment I am quite sure I have seen other Perl modules where you
can use native libraries (through the XS mechanism) or pure Perl
implementations.

Any objections or comments?

ciao
     Klaus