Fix thread termination on OSX

Author: shirok

ChangeLog

@@ -4,6 +4,10 @@
 	  Let thread-terminate! sends the signal again if thread is too busy
 	  to call Scm_SigCheck(), which makes the thread exit.
 	  https://github.com/shirok/Gauche/issues/1106
+	* src/gauche/pthread.h (GAUCHE_PTHREAD_SIGNAL): Use SIGUSR1 for
+	  thread termination singal on OSX, for it does not have real-time
+	  signals.  (OSX does no use signals but use thread_suspend /
+	  thread_resume in GC.)
 	* src/libextra.scm, test/thread-termination.scm: Add procedures
 	  specifically made to test thread-termination-by-signal behavior.
 

src/gauche/pthread.h

@@ -78,13 +78,18 @@ typedef pthread_t ScmInternalThread;
    provide them (on cygwin, SIGRTMIN == SIGRTMAX).   We use SIGPWR
    instead.
 */
-#if defined(SIGRTMIN) && !defined(GAUCHE_PTHREAD_SIGNAL)
-#  if !defined(__CYGWIN__)
-#    define GAUCHE_PTHREAD_SIGNAL (SIGRTMIN+5)
-#  else
-#    define GAUCHE_PTHREAD_SIGNAL SIGPWR
+#if !defined(GAUCHE_PTHREAD_SIGNAL)
+#  if defined(SIGRTMIN)
+#    if !defined(__CYGWIN__)
+#      define GAUCHE_PTHREAD_SIGNAL (SIGRTMIN+5)
+#    else
+#      define GAUCHE_PTHREAD_SIGNAL SIGPWR
+#    endif
+#  elif defined(__APPLE__)
+#    define GAUCHE_PTHREAD_SIGNAL SIGUSR1
 #  endif
-#endif /*defined(SIGRTMIN) && !defined(GAUCHE_PTHREAD_SIGNAL)*/
+#endif /*!defined(GAUCHE_PTHREAD_SIGNAL)*/
+
 
 /* ScmInternalMutex - a mutex structure.