to do two things:
1) properly set "recycle?" in inactive
2) easily check if we are renaming a removed vnode. without the
check, it was possible to enter a dirent in the file system for
a removed (and hence scheduled to be vcleaned) vnode. this would
lead to the succesful vget() of a clean vnode. the use of the
cleaned vnode was, however, less succesful, except for purposes
of crashing.
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