This reverts commit a57db845bb.
It breaks when building with -Dxinerama=false:
../Xext/shape.c: In function ‘ProcShapeRectangles’:
../Xext/shape.c:318:12: error: too few arguments to function
‘ShapeRectangles’; expected 2, have 1
318 | return ShapeRectangles(client);
| ^~~~~~~~~~~~~~~
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2055>