external/wayland: Uprev to 1.9.91

Update to the latest version of wayland that is being used in Chrome.
Most importantly, this update adds pointer events necessary for smooth
and kinetic srolling.

BUG=b:26917697
TEST=no functional change expected

Change-Id: Ie4020a3d9ff02b55c41921e1e41d517f54919d9e
28 files changed