qt5: Add qtvirtualkeyboard submodule

pkgs/development/libraries/qt-5/5.9/default.nix

···
       qtsvg = callPackage ../modules/qtsvg.nix {};
       qttools = callPackage ../modules/qttools.nix {};
       qttranslations = callPackage ../modules/qttranslations.nix {};
+      qtvirtualkeyboard = callPackage ../modules/qtvirtualkeyboard.nix {};
       qtwayland = callPackage ../modules/qtwayland.nix {};
       qtwebchannel = callPackage ../modules/qtwebchannel.nix {};
       qtwebengine = callPackage ../modules/qtwebengine.nix {};
···
         qtcharts qtconnectivity qtdeclarative qtdoc qtgraphicaleffects
         qtimageformats qtlocation qtmultimedia qtquickcontrols qtscript
         qtsensors qtserialport qtsvg qttools qttranslations qtwebsockets
-        qtx11extras qtxmlpatterns
+        qtx11extras qtxmlpatterns qtvirtualkeyboard
       ] ++ optional (!stdenv.isDarwin) qtwayland
         ++ optional (stdenv.isDarwin) qtmacextras);
 

pkgs/development/libraries/qt-5/modules/qtvirtualkeyboard.nix

···
+{ qtModule, qtbase, qtdeclarative, qtsvg, hunspell  }:
+
+qtModule {
+  name = "qtvirtualkeyboard";
+  qtInputs = [ qtbase qtdeclarative qtsvg hunspell ];
+}