With "xentoolcore_internal.h" been in LIBHEADER, it was installed. But
its dependency "_xentoolcore_list.h" wasn't installed so the header
couldn't be used anyway.
This patch also mean that the rule "headers.chk" doesn't check it
anymore as well.
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>