* gnu/packages/patches/netdde-csum.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/hurd.scm (netdde)[source]: Use it.
[arguments]: Do not assume x86, rather use actual ARCH in #:make-flags, and
follow upstream's "amd64" symlinking voodoo.
Change-Id: Ie825e56779dae2f489066569dc3c4405bac778c1