make 1.6.2.1

Update configure version strings for 1.6.2.1. Note that macos kext
can be of form XXXX.YY[.ZZ[(d|a|b|fc)NNN]] where d dev, a alpha,
b beta, f final candidate so we have no way to represent 1.6.2.1.
Switch to 1.6.3 dev 1 for macos.

Change-Id: I98f4371b8c020ba9ba6a98046690968bbae05744
Reviewed-on: http://gerrit.openafs.org/9600
Tested-by: Stephan Wiesand <stephan.wiesand@desy.de>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>