xinetd: expand DESTDIR patch to fix uninstall target

Expand the openWRT patch to fix xinetd's "uninstall" target,
so that buildroot's "xinetd-clean" removes the correct files.

Signed-off-by: Danomi Manchego <danomimanchego123@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>