binfmt: Don't schedule starthook if there are no constructors.

binfmt/binfmt_execmodule.c

@@ -276,7 +276,10 @@ int exec_module(FAR const struct binary_s *binp)
    * until the new task has been started.
    */
 
-  task_starthook(tcb, exec_ctors, (FAR void *)binp);
+  if (binp->nctors > 0)
+    {
+      task_starthook(tcb, exec_ctors, (FAR void *)binp);
+    }
 #endif
 
   /* Get the assigned pid before we start the task */

configs/stm32f4discovery/src/stm32_bringup.c

@@ -68,7 +68,7 @@
 
 #include "stm32f4discovery.h"
 
-/* Conditional logic in stm32f4discover.h will determine if certain features
+/* Conditional logic in stm32f4discovery.h will determine if certain features
  * are supported.  Tests for these features need to be made after including
  * stm32f4discovery.h.
  */

sched/task/task_start.c

@@ -89,7 +89,7 @@ void task_start(void)
   /* Execute the start hook if one has been registered */
 
 #ifdef CONFIG_SCHED_STARTHOOK
-  if (tcb->starthook)
+  if (tcb->starthook != NULL)
     {
       tcb->starthook(tcb->starthookarg);
     }