utsushi: Fix scanning

This commit fixes the problem reported in issue #177572.
Turns out that re-adding this line, which was removed in commit
526238b288, fixes the problem.

pkgs/misc/drivers/utsushi/default.nix

@@ -69,6 +69,7 @@ in stdenv.mkDerivation rec {
     touch $out/etc/sane.d/dll.conf
 
     # absolute paths to convert & tesseract
+    sed -i '/\[AC_DEFINE(\[HAVE_IMAGE_MAGICK\], \[1\])/a \ MAGICK_CONVERT="${imagemagick}/bin/convert"' configure.ac
     substituteInPlace filters/magick.cpp \
       --replace 'convert ' '${imagemagick}/bin/convert '
     substituteInPlace filters/reorient.cpp \