I installed the new thunar packages from unstable (0.9.0-1) but the problem with thunar-vfs-pixbuf-thumbnailer-1 and libpixbufloader-jpeg.so still exists. I get the same error message as before. So just adding libjpeg62-dev as a build dependency doesn't solve the problem. I don't know if it works for the amd64 packages but for the i386 packages it does not.