Compile with wlroots 0.15.1

- Honour size increments from WM_SIZE_HINTS, for example to allow
  xwayland terminal emulators to be resized to a width/height evenly
  divisible by the cell size. Written-by: @jlindgren90
- Implement cursor input for overlay popups. Written-by: @Consolatis

- Do not raise xwayland windows when deactivating (issue #270).
  Written-by: @Consolatis
- Restore drag mouse-bindings and proper double-click (issues #258 and
  #259). Written-by: @Consolatis
- Implement cursor input for unmanaged xwayland surfaces outside their
  parent view. Without this menus extending outside the main application
  window do not receive mouse input. Written-by: @jlindgren90
- Allow dragging scrollbar or selecting text even when moving cursor
  outside of the window (issue #241). Written-by: @Consolatis
- Fix positioning of xwayland views with multiple queued configure
  events. Written-by: @Consolatis
- Force a pointer enter event on the surface below the cursor when
  cycling views (issue #162). Written-by: @Consolatis
- Fix qt application crash on touchpad scroll (issue #225).
  Written-by: @Consolatis