kcachegrind: fix graphviz missing at runtime

pkgs/applications/kde/kcachegrind.nix

···
   mkDerivation, lib,
   extra-cmake-modules, kdoctools,
   karchive, ki18n, kio, perl, python3, php, qttools,
-  kdbusaddons
+  kdbusaddons, makeBinaryWrapper, graphviz
 }:
 
 mkDerivation {
···
     license = with lib.licenses; [ gpl2 ];
     maintainers = with lib.maintainers; [ orivej ];
   };
-  nativeBuildInputs = [ extra-cmake-modules kdoctools ];
+  nativeBuildInputs = [ extra-cmake-modules kdoctools makeBinaryWrapper ];
   buildInputs = [ karchive ki18n kio perl python3 php qttools kdbusaddons ];
+  postInstall = ''
+    wrapProgram $out/bin/kcachegrind \
+      --suffix PATH : "${lib.makeBinPath [ graphviz ]}"
+  '';
 }