Drop space in "vm object" lock name for a more clear wchan

[emaste]

Summary

Lock names are shown in top as a '*' followed by five characters of the name. *vmobj is a little more obvious and easier to search for than *vm ob.

[This is a little diff that I found hanging around in a WIP branch for many years]

[mjg]

can this either go in or get whacked? time for some stale rev cleaning

[markj]

It's a small change, I have no real objection, but I also don't feel strongly in favour of it. It makes this lock inconsistent with all the other VM lock names.