thread.c: suppress warnings [ci skip]

* thread.c (fill_thread_id_string): cast to void pointer to
  suppress warnings when pthread_t is not pointer type.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58532 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

thread.c

@@ -269,7 +269,7 @@ rb_thread_s_debug_set(VALUE self, VALUE val)
 #endif
 
 #ifndef fill_thread_id_str
-# define fill_thread_id_string(thid, buf) (thid)
+# define fill_thread_id_string(thid, buf) (void *)(thid)
 # define fill_thread_id_str(th) (void)0
 # define thread_id_str(th) ((void *)(th)->thread_id)
 # define PRI_THREAD_ID "p"