Fix unnecessary OS process acquisition
Fix unnecessary OS process acquisition

HotHead has had some latency issues lately related to couchjs spikes.
After looking harder we realized this is a bug in that
fabric_view_reduce will acquire an OS process wihtout checking if it
will actually need to use it. Simple fix is to just check the reduce
function source and conditionally acquire a couchjs process.

BugzId: 14007

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb