ANGLE: Fix releasing textures after we kill D3D11

Cherry-pick upstream commit cc4cd2925b9a4f1142a86df131345a861c9d7cd9
to fix crashes on exit.

Task-number: QTBUG-42772
Change-Id: Ib74be17f2b5fdd58f9e0568e1da74ba19e943019
Reviewed-by: Andrew Knight <andrew.knight@theqtcompany.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>