This patch changes the default worker count from ::processorcount to the new ::os_workers fact. ::os_workers is based on the number of processors (currently cpu/4) but is capped at a maximum of 8 worker processors. This is a much more reasonable default in general and prevents excessive resource consumption on systems with a large number of CPUs. Change-Id: Ib03ad48060349921b94fc4c794b3e02f41ad979d