AVCaptureDevice has API to work with camera flash on both iOS and OS X
(quite limited on OS X though) - so camera flash control can be implemented
in AVFoundation plugin.
Task-number: QTBUG-37996
Change-Id: Ie9aaed09a709e7d09ccc1cedded93a69fea93975
Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>