Giflib 5.1

update to compile with giflib >= 5.1

src/Image.cc

@@ -19,6 +19,12 @@ typedef struct {
 } gif_data_t;
 #endif
 
+#if GIFLIB_MAJOR > 5 || GIFLIB_MAJOR == 5 && GIFLIB_MINOR >= 1
+  #define GIF_CLOSE_FILE(gif) DGifCloseFile(gif, NULL)
+#else
+  #define GIF_CLOSE_FILE(gif) DGifCloseFile(gif)
+#endif
+
 /*
  * Read closure used by loadFromBuffer.
  */