As suggested by @kaspar030 the THREAD_CREATE_WOUT_YIELD flag was removed.
Now the sequence of output lines is identical in two cases: stdio via UART,
and stdio via CDC ACM (which needs a thread for that).
The expects have been changed to match the new situation, which is what
was already given in the CDC ACM case.
While trying python test libraries, like pytest, the automatic test collection
detects the `testNUM` functions as tests but does not know the `term` argument
and fails.
This declares them as private to only find `testfunc(child)` entry point.
Another solution could have been to use `testNUM(child)` and rename
`testfunc` to `main` but would not match other tests.
