[client] wayland: improve fractional scaling

avoids the 24.8 quantisation without introducing floating-point
equality/rounding behaviour throughout the Wayland state.

Closes #1257

client/displayservers/Wayland/cursor.c

@@ -183,7 +183,7 @@ void waylandCursorFree(void)
 
 void waylandCursorScaleChange(void)
 {
-  int newScale = ceil(wl_fixed_to_double(wlWm.scale));
+  int newScale = waylandScaleCeil(wlWm.scale);
   if (newScale == wlWm.cursorScale)
     return;