It's easier to order things in topological order than it is to
forward declare in one file for use only by one other file.

* tools/virsh.c (vshWatchJob, parseRateStr)
(vshDomainStateToString, vshDomainStateReasonToString)
(vshDomainControlStateToString, vshDomainVcpuStateToString): Drop
useless prototypes.
* tools/virsh-domain.c (vshWatchJob): Move earlier.