The commits avoids reading in and allocating memory for all potentially
threads, which are potentially currently not existent (but configured in the
policy beforehand). Instead the policy is read in and evaluated when a thread
is created and policy changes are solely applied to existing/running threads.
By this the commit avoids the increase of memory consumption during the
evaluation of policies during config ROM updates.
Issue #4333
This way, the redirected env sessions for the CPU burner are no longer
called directly by init. Init stays independent from the behavior of the
CPU balancer.
Issue #3837
Issue #4029
* Remove SPEC declarations from mk/spec
* Remove all board-specific REQUIRE declaratiions left
* Replace [have_spec <board>] run-script declarations with have_board where necessary
* Remove addition of BOARD variable to SPECS in toplevel Makefile
* Move board-specific directories in base-hw out of specs
