Fix character mirroring issue with HarfBuzz-NG

HarfBuzz-NG does character mirroring where appropriate.
A simple solution is to unset RightToLeft shaper flag when
text gets shaped with HB-NG. Instead, move the mirroring code
right to HB-old proxy function and decrease code duplication.

Change-Id: Icdcd50b73b3e6a43da4b85addc7d8f51edf86512
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Add suspend and resume event handling for WinRT

Task-number: QTBUG-35952

Change-Id: Icb4edb0f55c1d02dfbb5501df311b0fff87d2dc1
Reviewed-by: Andrew Knight <andrew.knight@digia.com>