Fix #392: ensure 'ready' condition is cleared on pidfile removal

A service with notify:pid is 'ready' when the pidfile has been created,
the converse also holds true -- when a pidfile is removed the service is
no longer 'ready'.

The state transition for the service has probably already been done, in
svc_set_state(), clearing all <service/foo/*> conditions when the PID
was collected.  The pidfile event may arrive later, so for completeness
we make sure the 'ready' condition is not recreated at least.

Problem introduced in 912a281 with the original supoport for service
readiness notification.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/service.h

@@ -42,7 +42,7 @@ int       service_timeout_after  (svc_t *svc, int timeout, void (*cb)(svc_t *svc
 int       service_timeout_cancel (svc_t *svc);
 
 void      service_forked         (svc_t *svc);
-void      service_ready          (svc_t *svc);
+void      service_ready          (svc_t *svc, int ready);
 
 int       service_stop           (svc_t *svc);
 int       service_step           (svc_t *svc);