xen/test/livepatch/Makefile: Install in DESTDIR/usr/lib/debug/xen-livepatch
Dumping these patch files in /usr/lib/debug/xen-*.livepatch is a bit
ugly.
Also, refactor the Makefile to have a LIVEPATCHES variable, to reduce
repetition.
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Jan Beulich <jbeulich@suse.com> Acked-by: Wei Liu <wei.liu2@citrix.com> Release-acked-by: Julien Grall <julien.grall@arm.com>