Source: Arch Linux commits
https://mailman.archlinux.org/pipermail/arch-commits/2013-April/197196.html
Copied: jbig2dec/repos/community-staging-x86_64/jbig2dec-0.11-libpng15.patch (from rev 89413, jbig2dec/trunk/jbig2dec-0.11-libpng15.patch)
Modified for jbig2dec that comes with mupdf-1.4

--- jbig2_image_png.c
+++ jbig2_image_png.c
@@ -33,7 +33,7 @@
 {
     png_size_t check;
 
-    check = fwrite(data, 1, length, (png_FILE_p)png_ptr->io_ptr);
+    check = fwrite(data, 1, length, (png_FILE_p)png_get_io_ptr(png_ptr));
     if (check != length) {
       png_error(png_ptr, "Write Error");
     }
@@ -43,7 +43,7 @@
 jbig2_png_flush(png_structp png_ptr)
 {
     png_FILE_p io_ptr;
-    io_ptr = (png_FILE_p)CVT_PTR((png_ptr->io_ptr));
+    io_ptr = (png_FILE_p)png_get_io_ptr(png_ptr);
     if (io_ptr != NULL)
         fflush(io_ptr);
 }