HPCC-10049 Retrieve data for displaying cumulative Roxie graphs

A new WsWorkunits/WUQueryGetGraph method is added to retrieve data for
displaying cumulative Roxie graphs. The method calls control:queryStats
to get the data for displaying cumulative Roxie graphs.

And two small fixes: a. a compiling warning; b. a better time out for using
control:getQueryXrefInfo.

Signed-off-by: Kevin Wang kevin.wang@lexisnexis.com