Fixed issue in load_checkpoint.sh where the critical 'p4d -xu' step
can fail due to lack of a license file with enough users for the
data set. With this fix (borrowed from upgrade.sh), the critical
upgrade step succeeds, and the user is not left with a failure in
the middle of processing that would require manual cleanup.
The p4d server will still refuse to start without a proper license
later in the process, but at that we're at a cleaner break point in
processing, and the failure mode is clearer to admins.