Incorrect raw-handle to MacOs, fix included

[sanbox-irl]

Hello!

In this PR, #962, at some point, the author included this line in their MacOS implementation:

                    ns_view: 0 as *mut libc::c_void, // consumer of RawWindowHandle should determine this

This was, as far as I can see, a mistake. By default, using sdl2 and wgpu, this will create a crash, as ns_view must be well defined for WGPU to work, and nothing implies that this value is incorrect. Moreover, on a philosophical level, the trait and its cross-platform nature is to force sdl2 and other windowing wrappers to correctly give these handles to graphics libraries like WGPU, so it seems to me that SDL2 should properly define ns_view.

The example here shows the workflow required: 92b4309

My question now is...why? Why aren't we providing the correct ns_view by default, and why do we expect users to do this strange song and dance?

[nightfly19]

There seem to have been some changes to raw-window-handle and WGPU since this issue was opened. I've updated the WindowWrapper hack and am posting it here in case it helps anyone.
wrapper.rs.txt

[toyboot4e]

Great! One year ago raw-window-handle was 0.3, while it's 0.4 toaday.

[joseluis]

this should be closed by #1225

BTW now raw-window-handle is 0.5