* Include proper header file in 'tools' for configuration macros.
* Include pthread_np.h from pthread_stop_world.c on OpenBSD.
* Move GC_get_suspend/thr_restart_signal to misc.c for NaCl and OpenBSD.
+* Postpone the suspend signal in GC_dirty_init only if used to stop world.
* Recognize GC_DONT_GC macro in gc.h (causes GC_INIT to turn off GC).
* Recognize GC_SIG_SUSPEND and GC_SIG_THR_RESTART tuning macros in gc.h.
* Replace SIG_SUSPEND/THR_RESTART macros to variables in pthread_stop_world.