Reorder operation to eliminate possible overflow

Author: oschwald

src/main/java/com/maxmind/db/MultiBuffer.java

@@ -155,7 +155,7 @@ public byte get() {
     /** {@inheritDoc} */
     @Override
     public Buffer get(byte[] dst) {
-        if (position + dst.length > limit) {
+        if (position > limit - dst.length) {
             throw new IndexOutOfBoundsException(
                     "Read exceeds limit: position=" + position
                             + ", length=" + dst.length
@@ -359,4 +359,4 @@ public static MultiBuffer mapFromChannel(FileChannel channel) throws IOException
         }
         return new MultiBuffer(buffers, DEFAULT_CHUNK_SIZE);
     }
-}
+}