chore: keep GDI fontengine on Windows for now (#5710)

cmake/resources/generate_resources.cmake

@@ -88,6 +88,15 @@ if (WIN32)
     list(APPEND RES_AUTOGEN_FILES "${CMAKE_BINARY_DIR}/autogen/windows.rc")
 endif ()
 
+set(WINDOWS_ARGUMENTS "@Invalid()") # empty QVariant() in QSettings
+if (CHATTERINO_USE_GDI_FONTENGINE AND Qt${MAJOR_QT_VERSION}_VERSION VERSION_GREATER_EQUAL "6.8.0")
+    message(STATUS "Using legacy GDI fontengine")
+    set(WINDOWS_ARGUMENTS "fontengine=gdi")
+endif ()
+
+configure_file("${CMAKE_CURRENT_LIST_DIR}/qt.conf.in" "${CMAKE_SOURCE_DIR}/resources/qt.conf")
+list(APPEND RES_AUTOGEN_FILES "${CMAKE_SOURCE_DIR}/resources/qt.conf")
+
 list(APPEND RES_AUTOGEN_FILES
         "${CMAKE_SOURCE_DIR}/resources/resources_autogenerated.qrc"
         "${CMAKE_BINARY_DIR}/autogen/ResourcesAutogen.cpp"

cmake/resources/qt.conf.in

@@ -0,0 +1,2 @@
+[Platforms]
+WindowsArguments = ${WINDOWS_ARGUMENTS}

cmake/resources/resources_autogenerated.qrc.in

@@ -6,4 +6,7 @@
   <qresource prefix="/">
 @RES_RESOURCES_CONTENT@
   </qresource>
+  <qresource prefix="/qt/etc">
+    <file>qt.conf</file>
+  </qresource>
 </RCC>