Make it possible to build without underscore
Make it possible to build without underscore

areOutputPrefix is only present when underscore is enabled,
and --nop only means something in the same condition,
so we don't need to add it when invoking buildsys

Change-Id: I789f858a9198f67cd3702dd66b7d2d774926d9c7
Reviewed-by: John Collis <ae1a4723500598651824221cfdee02d50e086870@alliedtelesis.co.nz>

ATL-NZ/buildsyspp,alliedtelesis/buildsyspp