livepatch-gcc: Ignore built_in.o and prelink.o object files

livepatch-gcc: Ignore built_in.o and prelink.o object files

Do not copy over the built_in.o and prelink.o object files when they
get rebuilt as they are used for transient linking by Xen's build
system.

Signed-off-by: Pawel Wieczorkiewicz <wipawel@amazon.de>
Reviewed-by: Martin Pohlack <mpohlack@amazon.de>
Reviewed-by: Petre Eftime <epetre@amazon.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>