configure on Windows: Store result of V8 configuration

Otherwise V8 won't be built (there's a contains()
check in src.pro).

Change-Id: Iba65e85baae1e80800e5ca0da49fde8958dfd659
Reviewed-on: http://codereview.qt-project.org/4524
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

tools/configure/configureapp.cpp

@@ -2727,6 +2727,9 @@ void Configure::generateOutputVars()
     // We currently have no switch for QtSvg, so add it unconditionally.
     qtConfig += "svg";
 
+    if (dictionary[ "V8" ] == "yes")
+        qtConfig += "v8";
+
     // Add config levels --------------------------------------------
     QStringList possible_configs = QStringList()
         << "minimal"