Wayland: Swap 90 and 270 degree transforms
The previous interpretation was not conform with the Wayland spec, see: https://gitlab.freedesktop.org/wayland/weston/issues/99
This MR make Mutter compatible with the changes in https://gitlab.freedesktop.org/wayland/weston/merge_requests/383
Fixes #1045 (comment 712038)
Edited by Robert Mader