This function makes a better replacement for gdk_display_get_core_pointer(), wherever it might yet be needed, for XI2 resorts to XIGetClientPointer(), for the others return the only core pointer. https://bugzilla.gnome.org/show_bug.cgi?id=621685
The abicheck script was hardcoding assumptions about XI2 being used, making it fail on e.g. RHEL5.