CMake: Remove some dead code

The code was added as part of
a6ccef651d
but the important bits were removed as part of
c431e2d33c

Change-Id: I6ba7bffa2bfdbeae2c92cd9ffeaa5f31771eedde
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

cmake/QtModuleHelpers.cmake

@@ -498,9 +498,7 @@ set(QT_CMAKE_EXPORT_NAMESPACE ${QT_CMAKE_EXPORT_NAMESPACE})")
     endif()
 
     # Generate metatypes
-    set(QT_MODULE_HAS_META_TYPES_FILE FALSE)
     if (${arg_GENERATE_METATYPES})
-        set(QT_MODULE_HAS_META_TYPES_FILE TRUE)
         set(metatypes_install_dir ${INSTALL_LIBDIR}/metatypes)
         set(args)
         if (NOT QT_WILL_INSTALL)