Add a start hook that can be setup to call a function in the context of a new thread before the new threads main() has been called.

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5571 42af7a65-404d-4744-a932-0658087f49c3

apps/examples/elf/tests/signal/signal.c

@@ -161,7 +161,7 @@ int main(int argc, char **argv)
   /* Send SIGUSR1 to ourselves via kill() */
 
   printf("Kill-ing SIGUSR1 from pid=%d\n", mypid);
-  status = kill(0, SIGUSR1);
+  status = kill(mypid, SIGUSR1);
   if (status != 0)
     {
       fprintf(stderr, "Failed to kill SIGUSR1, errno=%d\n", errno);

apps/examples/nxflat/tests/signal/signal.c

@@ -161,7 +161,7 @@ int main(int argc, char **argv)
   /* Send SIGUSR1 to ourselves via kill() */
 
   printf("Kill-ing SIGUSR1 from pid=%d\n", mypid);
-  status = kill(0, SIGUSR1);
+  status = kill(mypid, SIGUSR1);
   if (status != 0)
     {
       fprintf(stderr, "Failed to kill SIGUSR1, errno=%d\n", errno);