Remove overflow check from update_nextCid
The rx_nextCid global has been an unsigned type since
http://gerrit.openafs.org/11106 (which was actually merged before
the refactoring of overflow check to avoid signed integer overflow)
and thus there is no need to avoid signed overflow. The per-connection
cid has been unsigned since the IBM import.
The natural unsigned behavior on overflow of wrapping is the desired
behvaior here, so just remove the extra logic and always increment.
Change-Id: I2d9fd24082b762eb871199da3ac1cc0983764585
Reviewed-on: https://gerrit.openafs.org/14496
Reviewed-by: Jeffrey Hutzelman <jhutz@cmu.edu>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: Benjamin Kaduk <kaduk@mit.edu>