lcms2: Stop propagating dependencies

These were propagated from the beginning (2d9d69c)
but I cannot see any reason for that. They are not mentioned in the pkg-config file.
And the three libraries only appear to be used by jpgicc/tificc programs.

pkgs/by-name/lc/lcms2/package.nix

@@ -22,7 +22,7 @@ stdenv.mkDerivation rec {
     "out"
   ];
 
-  propagatedBuildInputs = [
+  buildInputs = [
     libtiff
     libjpeg
     zlib