init: Retain traditional restart behavior for critical and oneshot services.

Adds an SVC_RESTART state that's used for an explicit "restart" of a
running service.  This retains the traditional restart behavior for
critical and oneshot services (previously altered by 7e36edd8), whereby
these services are "simply restarted" instead of counting as a crash (for a
critical serivce) or going into the disabled state (for a oneshot service).
diff --git a/init/signal_handler.c b/init/signal_handler.c
index b170132..672904d 100644
--- a/init/signal_handler.c
+++ b/init/signal_handler.c
@@ -63,7 +63,7 @@
 
     NOTICE("process '%s', pid %d exited\n", svc->name, pid);
 
-    if (!(svc->flags & SVC_ONESHOT)) {
+    if (!(svc->flags & SVC_ONESHOT) || (svc->flags & SVC_RESTART)) {
         kill(-pid, SIGKILL);
         NOTICE("process '%s' killing any children in process group\n", svc->name);
     }
@@ -78,8 +78,9 @@
     svc->pid = 0;
     svc->flags &= (~SVC_RUNNING);
 
-        /* oneshot processes go into the disabled state on exit */
-    if (svc->flags & SVC_ONESHOT) {
+        /* oneshot processes go into the disabled state on exit,
+         * except when manually restarted. */
+    if ((svc->flags & SVC_ONESHOT) && !(svc->flags & SVC_RESTART)) {
         svc->flags |= SVC_DISABLED;
     }
 
@@ -90,7 +91,7 @@
     }
 
     now = gettime();
-    if (svc->flags & SVC_CRITICAL) {
+    if ((svc->flags & SVC_CRITICAL) && !(svc->flags & SVC_RESTART)) {
         if (svc->time_crashed + CRITICAL_CRASH_WINDOW >= now) {
             if (++svc->nr_crashed > CRITICAL_CRASH_THRESHOLD) {
                 ERROR("critical process '%s' exited %d times in %d minutes; "
@@ -105,6 +106,7 @@
         }
     }
 
+    svc->flags &= (~SVC_RESTART);
     svc->flags |= SVC_RESTARTING;
 
     /* Execute all onrestart commands for this service. */