Implement as generic "@Nx" support in an exported
qt_findAtNxFile function.
3x devices now get one extra file existence test
in cases where @3x versions are not present. 1x
devices are still on the fast path where there are
no extra file system accesses.
Add an @3x image to the highdpi manual test.
Change-Id: I4ce3fc245ada01ea410abe1443ceb1e3abf7c17f
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@theqtcompany.com>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@theqtcompany.com>
