Add the "-s slice" option to the Linux version of mkextrafs.pl.
Add the "-s slice" option to the Linux version of mkextrafs.pl.

So we can specify a different slice (partition) to create the filesystem on.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome