jobs: Wake up an event loop if needed

A queued job must be treated. It was not the case
when the job was queued from a foreign thread.
This change detect that a potential hang exists
and wake up an event loop to avoid it.

Bug-AGL: SPEC-2809

Signed-off-by: José Bollo <jose.bollo@iot.bzh>
Change-Id: Id12d32771ea37df5f5f2e208ec9645a6c4b0d0ab