Fix AbstractDiskHttpData int conversion from long

Motivations:
The chunkSize might be oversized after comparison (size being > of int
capacity) if file size is bigger than an integer.

Modifications:
Change it to long.

Result:
There is no more int oversized.

Same fix for 4.1 and Master

codec-http/src/main/java/io/netty/handler/codec/http/multipart/AbstractDiskHttpData.java

@@ -341,11 +341,11 @@ public boolean renameTo(File dest) throws IOException {
             FileOutputStream outputStream = new FileOutputStream(dest);
             FileChannel in = inputStream.getChannel();
             FileChannel out = outputStream.getChannel();
-            int chunkSize = 8196;
+            long chunkSize = 8196;
             long position = 0;
             while (position < size) {
                 if (chunkSize < size - position) {
-                    chunkSize = (int) (size - position);
+                    chunkSize = size - position;
                 }
                 position += in.transferTo(position, chunkSize , out);
             }