sane-backends: propagate libjpeg library path

pkgs/applications/graphics/sane/backends/generic.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchurl
-, avahi, libusb1, libv4l, net_snmp
+, avahi, libjpeg, libusb1, libv4l, net_snmp
 , gettext, pkgconfig
 
 # List of { src name backend } attibute sets - see installFirmware below:
@@ -50,6 +50,9 @@ stdenv.mkDerivation {
     mkdir -p $out/etc/udev/rules.d/
     ./tools/sane-desc -m udev > $out/etc/udev/rules.d/49-libsane.rules || \
     cp tools/udev/libsane.rules $out/etc/udev/rules.d/49-libsane.rules
+
+    substituteInPlace $out/lib/libsane.la \
+      --replace "-ljpeg" "-L${libjpeg}/lib -ljpeg"
   '' + stdenv.lib.concatStrings (builtins.map installFirmware compatFirmware);
 
   meta = with stdenv.lib; {