add a bitarray into struct osThreadDef_t to indicate whether the
thread is used or not, then we can get the first available thread
by searching this array when creating a new thread, and update this
array to add a free thread when terminating a thread.
Signed-off-by: Chen Peng1 <peng1.chen@intel.com>
Move cmsis OS apis under subsystem/portability. Those are not libraries
and only serve to provide a level of abstraction using the CMSIS OS APIs
to existing Zephyr interfaces.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>