xwayland: Add break statements in pointer_handle_axis
Fixes accidentally taking the WL_POINTER_AXIS_HORIZONTAL_SCROLL case as well after the WL_POINTER_AXIS_VERTICAL_SCROLL case, which resulted in vertical wheel events triggering both vertical and horizontal scrolling.
Fixes: e37eeb7a ("xwayland: Aggregate scroll axis events to fix kinetic scrolling") Closes: #1367 (closed)