[xwayland-22.1] Backport fixes
Backport several fixes cherry-picked from the master branch, namely:
- e37eeb7a xwayland: Aggregate scroll axis events to fix kinetic scrolling
- 18f91b95 xkb: fix some possible memleaks in XkbGetKbdByName
- 44ae6f44 xkb: length-check XkbGetKbdByName before accessing the fields
- 1bb7767f xkb: length-check XkbListComponents before accessing the fields
- 11beef0b xkb: proof GetCountedString against request length attacks
- 2efa6d65 dix: Fix overzealous caching of ResourceClientBits()
- 354e39ee xwayland: correct the type for the discrete scroll events
- f0b2eeaf xwayland: Add break statements in pointer_handle_axis
- 79c572fb xkb: Avoid length-check failure on empty strings.
- 4603d644 ci: remove redundant slash in libxcvt repository url
- f778b56a dix: Skip more code in SetRootClip for ROOT_CLIP_INPUT_ONLY
- a77d95af xwayland: Prevent Xserver grabs with rootless