advancecomp: version number correctly embedded in binaries

without this fix, binaries report their version number as "vnone"
which for example stops `image_optim` from using `advpng` (refuses
to use it not being able to tell what version number it has)

pkgs/tools/compression/advancecomp/default.nix

@@ -28,6 +28,13 @@ stdenv.mkDerivation rec {
     })
   ];
 
+  # autover.sh relies on 'git describe', which obviously doesn't work as we're not cloning
+  # the full git repo. so we have to put the version number in `.version`, otherwise
+  # the binaries get built reporting "none" as their version number.
+  postPatch = ''
+    echo "${version}" >.version
+  '';
+
   meta = with stdenv.lib; {
     description = ''A set of tools to optimize deflate-compressed files'';
     license = licenses.gpl3 ;