Add config glue for amd64_nbsd70 and i386_nbsd70 sysnames

Change-Id: I2d0b6848f96aab8d68a41fb6d5892284fca987ad
Reviewed-on: http://gerrit.openafs.org/10257
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>