This fixes test failures of packages that use Open MPI, whereby UCX
would error out due to /sys/class/net being unavailable in the build
chroot that the daemon sets up.
* gnu/packages/patches/ucx-tcp-iface-ioctl.patch: New file.
* gnu/packages/fabric-management.scm (ucx)[source]: Use it.
* gnu/local.mk (dist_patch_DATA): Add it.
