use WS_EX_NOREDIRECTIONBITMAP direct-composition app

[ekicyou]

with_no_redirection_bitmap API added to master branch of winit=0.16.0.
It is useful for direct-composition samples.

resubmit #2838 PR,
Thanks! #2878, #2877.

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This change is 

[SimonSapin]

Looks good, thanks!

@bors-servo r+

I didn’t know what WS_EX_NOREDIRECTIONBITMAP is, and https://docs.microsoft.com/en-us/windows/desktop/winmsg/extended-window-styles was not super informative. https://stackoverflow.com/questions/38179033/when-should-ws-ex-noredirectionbitmap-be-used and https://msdn.microsoft.com/magazine/dn745861.aspx have a better explanation. (That last article would have been useful to find while figuring out how to use DirectComposition to make this demo!)

For posterity, this is what the demo app looks like now (with in the background the terminal where I compiled it).

[bors-servo]

📌 Commit d7ef6a2 has been approved by SimonSapin

[bors-servo]

⌛ Testing commit d7ef6a2 with merge c540acf...

[bors-servo]

☀️ Test successful - status-appveyor, status-taskcluster
Approved by: SimonSapin
Pushing c540acf to master...

[ekicyou]

Thank you for adding explanation.
Although commit is dare to mention .with_decorations(true),When false, the world without windows spreads.

Even though it is Windows :-)

By using WS_EX_NOREDIRECTIONBITMAP and DirectComposition, you can develop applications without windows by GPU rendering (2D / 3D) (such as desktop mascot).