kernel: Cleanup, unify _add_thread_to_ready_q() and _ready_thread()

The scheduler exposed two APIs to do the same thing:
_add_thread_to_ready_q() was a low level primitive that in most cases
was wrapped by _ready_thread(), which also (1) checks that the thread
_is_ready() or exits, (2) flags the thread as "started" to handle the
case of a thread running for the first time out of a waitq timeout,
and (3) signals a logger event.

As it turns out, all existing usage was already checking case #1.
Case #2 can be better handled in the timeout resume path instead of on
every call.  And case #3 was probably wrong to have been skipping
anyway (there were paths that could make a thread runnable without
logging).

Now _add_thread_to_ready_q() is an internal scheduler API, as it
probably always should have been.

This also moves some asserts from the inline _ready_thread() wrapper
to the underlying true function for code size reasons, otherwise the
extra use of the inline added by this patch blows past code size
limits on Quark D2000.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>
6 files changed