HTCONDOR-782: Make python2 optional if boost is missing.
HTCONDOR-782: Make python2 optional if boost is missing.

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor