HPCC-11692 Spurious "unregistered query" errors

The queryHash is now derived from (among other things) the timestamps of the
files used by the query. Unfortunately the calculation of the hash included
the uninitialized filler byte in the CDateTiem structure.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Not for this commit, but might be worth adding a couple of macro, to do e.g.
ROXIETRACE(8, "getQueryHash: %s %"I64F"u from dll", id, hashValue);