Detect when v3 services get disabled after HUP.

Remove v3 optimization which made Tor not detect disabling services.

This optimization is not so needed because we only call that function after HUP
anyway.

Fixes bug #25761.

changes/bug25761

@@ -0,0 +1,3 @@
+  o Major bugfixes (onion service):
+    - Correctly detect when onion services get disabled after HUP.
+      Fixes bug 25761; bugfix on 0.3.2.1.

src/or/hs_service.c

@@ -859,11 +859,6 @@ register_all_services(void)
 
   tor_assert(hs_service_staging_list);
 
-  /* We'll save us some allocation and computing time. */
-  if (smartlist_len(hs_service_staging_list) == 0) {
-    return;
-  }
-
   /* Allocate a new map that will replace the current one. */
   new_service_map = tor_malloc_zero(sizeof(*new_service_map));
   HT_INIT(hs_service_ht, new_service_map);