thread.c: refine enums

* ext/thread/thread.c: remove unnecessary enum values and add end
  of enumerations.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49766 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/thread/thread.c

@@ -1,14 +1,16 @@
 #include <ruby.h>
 
 enum {
-    CONDVAR_WAITERS = 0
+    CONDVAR_WAITERS,
+    END_CONDVAR
 };
 
 enum {
-    QUEUE_QUE       = 0,
-    QUEUE_WAITERS   = 1,
-    SZQUEUE_WAITERS = 2,
-    SZQUEUE_MAX     = 3
+    QUEUE_QUE,
+    QUEUE_WAITERS,
+    SZQUEUE_WAITERS,
+    SZQUEUE_MAX,
+    END_QUEUE
 };
 
 #define GET_CONDVAR_WAITERS(cv) get_array((cv), CONDVAR_WAITERS)