make default NUM_CPUS available to reference in a config file #4197
This commit also adds DETECTED_CPUS and DETECTED_PHYSICAL_CPUS to
the config system as automatic non-overridable param values; It
changes the sysapi into an api for quering the actual number of CPUS.
After this change code that wishes to use NUM_CPUS should query via param
instead of sysapi.
===VersionHistory:Pending===