This adds a new platform named wasm-emscripten-64
which sets the build and link argument -MEMORY64
You may see this warning, please ignore at your own discretion:
em++: warning: -sMEMORY64 is still experimental. Many features may not work.
[-Wexperimental]
Fixes: QTBUG-104891
Change-Id: I8d3150d239ba72dbef5c2352e0171d6cfbe51b59
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
