vtk_7: Fix enableQt build

VTK 7 builds with Qt 4 by default but we only support Qt 5, so let’s switch to that.
Also Qt changed some headers so let’s backport the VTK patch to fix the build.

pkgs/development/libraries/vtk/7.x.nix

@@ -2,13 +2,21 @@ import ./generic.nix {
   majorVersion = "7.1";
   minorVersion = "1";
   sourceSha256 = "0nm7xwwj7rnsxjdv2ssviys8nhci4n9iiiqm2y14s520hl2dsp1d";
-  patchesToFetch = [{
-   url = "https://gitlab.kitware.com/vtk/vtk/-/commit/706f1b397df09a27ab8981ab9464547028d0c322.diff";
-   sha256 = "1q3pi5h40g05pzpbqp75xlgzvbfvyw8raza51svmi7d8dlslqybx";
- }
- {
-    url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/sci-libs/vtk/files/vtk-8.2.0-gcc-10.patch?id=c4256f68d3589570443075eccbbafacf661f785f";
-    sha256 = "sha256:0bpwrdfmi15grsg4jy7bzj2z6511a0c160cmw5lsi65aabyh7cl5";
-  }
+  patchesToFetch = [
+    {
+      url = "https://gitlab.kitware.com/vtk/vtk/-/commit/706f1b397df09a27ab8981ab9464547028d0c322.diff";
+      sha256 = "1q3pi5h40g05pzpbqp75xlgzvbfvyw8raza51svmi7d8dlslqybx";
+    }
+
+    {
+      url = "https://gitweb.gentoo.org/repo/gentoo.git/plain/sci-libs/vtk/files/vtk-8.2.0-gcc-10.patch?id=c4256f68d3589570443075eccbbafacf661f785f";
+      sha256 = "sha256:0bpwrdfmi15grsg4jy7bzj2z6511a0c160cmw5lsi65aabyh7cl5";
+    }
+
+    # Add missing include required with recent Qt.
+    {
+      url = "https://gitlab.kitware.com/vtk/vtk/-/commit/797f28697d5ba50c1fa2bc5596af626a3c277826.diff";
+      sha256 = "BFjoKws1hVD3Ly9RS4lGN62J6RTyI1E8ATHrZdzg7ds=";
+    }
   ];
 }

pkgs/development/libraries/vtk/generic.nix

@@ -75,6 +75,8 @@ in stdenv.mkDerivation rec {
     "-DCMAKE_INSTALL_BINDIR=bin"
   ] ++ optionals enableQt [
     "-D${if lib.versionOlder version "9.0" then "VTK_Group_Qt:BOOL=ON" else "VTK_GROUP_ENABLE_Qt:STRING=YES"}"
+  ] ++ optionals (enableQt && lib.versionOlder version "8.0") [
+    "-DVTK_QT_VERSION=5"
   ]
     ++ optionals stdenv.isDarwin [ "-DOPENGL_INCLUDE_DIR=${OpenGL}/Library/Frameworks" ]
     ++ optionals enablePython [