jobs: Fix infinite wait lock

The binder was sometime locked until an external
event comes. This was discovered during stressing
startup test that don't expect external inputs and
that then waits for always without terminating.

The issue came from a little hole in the management
of the state of evmgr object. By design the evmgr
has to be synchronised against concurrent accesses
not by itself but by the integration. However, the
state of "running" wasn't set in the code protected
against concurent accesses. The new function allows
the integrator to correctly set the state before
releasing protection.

Bug-AGL: SPEC-2459

Signed-off-by: José Bollo <jose.bollo@iot.bzh>
Change-Id: Id75fd97c06d69666ced912a0a61380573dab31af