Cleaned up process table structure: removed p_type, p_pendcount.

Removed stop sequence when MINIX is shut down.
Disabled send mask checks --- to be replaced by proper mechanism.
Fixed bug relating to 'shutdown -x'.
Simplified clock accounting of realtime.
Updated Makefiles for mkdept script.

kernel/exception.c

@@ -53,7 +53,7 @@ unsigned vec_nr;
 	return;
   }
 
-  if (k_reenter == 0 && ! istaskp(saved_proc)) {
+  if (k_reenter == 0 && ! iskernelp(saved_proc)) {
 	cause_sig(proc_nr(saved_proc), ep->signum);
 	return;
   }