[Bugfix] Issue#54 The ACK Receiver Thread didn't handle signal correctly

 Description
 ===========
 Ack Receiver thread will be launched when booting the MySQL server,
 but it is before the signal register, so the thread can receive the signal,
 and can't deal with shutdown smoothly like 'SIGTERM, SIGHUP'.

sql/mysqld.cc

@@ -4103,12 +4103,6 @@ int init_common_variables()
   if (thread_running_high_watermark == 0)
     thread_running_high_watermark= max_connections;
 
-#ifdef HAVE_REPLICATION
-  if (repl_semisync_master.initObject() ||
-      repl_semisync_slave.initObject())
-    return 1;
-#endif
-
   unireg_init(opt_specialflag); /* Set up extern variabels */
   if (!(my_default_lc_messages=
         my_locale_by_name(lc_messages)))
@@ -5537,6 +5531,12 @@ int mysqld_main(int argc, char **argv)
 
   my_init_signals();
 
+#ifdef HAVE_REPLICATION
+  if (repl_semisync_master.initObject() ||
+      repl_semisync_slave.initObject())
+    unireg_abort(1);        // Will do exit
+#endif
+
   size_t guardize= 0;
   int retval= pthread_attr_getguardsize(&connection_attrib, &guardize);
   DBUG_ASSERT(retval == 0);