Fix compile error when USE_COPY_FILE_RANGE is defined but not USE_SENDFILE

io.c: Variable and label definition are necessary in both cases.

From: Lars Kanis <lars@greiz-reinsdorf.de>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62321 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

io.c

@@ -11133,7 +11133,7 @@ static void *
 nogvl_copy_stream_func(void *arg)
 {
     struct copy_stream_struct *stp = (struct copy_stream_struct *)arg;
-#ifdef USE_SENDFILE
+#if defined(USE_SENDFILE) || defined(USE_COPY_FILE_RANGE)
     int ret;
 #endif
 
@@ -11151,7 +11151,7 @@ nogvl_copy_stream_func(void *arg)
 
     nogvl_copy_stream_read_write(stp);
 
-#ifdef USE_SENDFILE
+#if defined(USE_SENDFILE) || defined(USE_COPY_FILE_RANGE)
   finish:
 #endif
     return 0;