This avoids hanging upon second boot and ensures a declarative /hurd and /dev.
* gnu/packages/patches/hurd-startup.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/hurd.scm (hurd): Use it.
[arguments]: In stage create-runsystem remove /dev/urandom.
Change-Id: Ifcca5562c297204735c35132820a32ca0f273677
