patch 8.0.0728: the terminal structure is never freed

Problem:    The terminal structure is never freed.
Solution:   Free the structure and unreference what it contains.
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 428d7a4..33307e5 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -6772,7 +6772,7 @@
     job_T	*job = get_job_arg(&argvars[0]);
 
     if (job != NULL)
-	rettv->vval.v_number = job_stop(job, argvars);
+	rettv->vval.v_number = job_stop(job, argvars, NULL);
 }
 #endif