This is mostly a rewrite of src/afs/afs_cell.c, and associated changes

This is mostly a rewrite of src/afs/afs_cell.c, and associated changes
to other things.  Features of the new cell code:

 * Persistent name-to-cell-number mapping across reboots, to ensure the
   cell numbers in the dcache are meaningful.  Stored in the new cache
   file, /usr/vice/cache/CellInfo.
 * Allow cmdebug to query the cell number to cell name mapping.
 * Allow clients to have an empty CellServDB as long as AFSDB is enabled
   and ThisCell has AFSDB records.
 * The home cell retains the setuid bit even if looked up via AFSDB.
 * Dynroot gets its own cell, rather than piggybacking on cell 1.
 * Cell 1 is no longer special; cell numbers are now semi-opaque.
 * Convert cell traversal code to using GetCellByIndex rather than
   directly poking at CellLRU / afs_xcell.
 * Separate cells from aliases, which shouldn't have been the same
   in the first place.
 * Cleaner code (IMHO).

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This delta was composed from multiple commits as part of the CVS->Git migration.
The checkin message with each commit was inconsistent.
The following are the additional commit messages.
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make the arguments afs_CellNumValid takes match the prototype (since it
really is a afs_int32 it looks like)

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update irix to deal

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update irix to deal

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Fix some more references to the now-nonexistant cell->index