tools/include: generate a _xen_list.h file

tools/include: generate a _xen_list.h file

Today tools/include contains two basically identical header files
generated from the same source. They just differ by the used name space
and they are being generated from different Makefiles via a perl
script.

Prepare to have only one such header by using a more generic namespace
"XEN" for _xen_list.h.

As the original header hasn't been updated in the Xen tree since its
introduction about 10 years ago, and the updates of FreeBSD side have
mostly covered BSD internal debugging aids, just don't generate the
new header during build, especially as using the current FreeBSD
version of the file would require some updates of the perl script,
which are potentially more work than just doing the needed editing by
hand. Additionally this enables to remove the not needed debugging
extensions of FreeBSD.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>