HPCC-12599 Option in Roxie to bind queries to cores

Set coresPerQuery in RoxieTopology.xml or bindCores in workunit
debug values ir in query XML to indicate that execution of this
query should be bould to at most N cores out of the ones that
the Roxie process itself is bould to.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
calculate processCores in here (see comment below)