Add a missing client-detached hook when the server shuts down, and do

not exit until jobs started from run-shell/if-shell have finished (add a
job flags member and a flag to indicate other jobs). GitHub issue 1245.

job.c

@@ -44,7 +44,7 @@ struct joblist	all_jobs = LIST_HEAD_INITIALIZER(all_jobs);
 struct job *
 job_run(const char *cmd, struct session *s, const char *cwd,
     job_update_cb updatecb, job_complete_cb completecb, job_free_cb freecb,
-    void *data)
+    void *data, int flags)
 {
 	struct job	*job;
 	struct environ	*env;
@@ -111,6 +111,7 @@ job_run(const char *cmd, struct session *s, const char *cwd,
 
 	job = xmalloc(sizeof *job);
 	job->state = JOB_RUNNING;
+	job->flags = flags;
 
 	job->cmd = xstrdup(cmd);
 	job->pid = pid;