window: fix meta_window_get_titlebar_rect

At least two places before 90b36abe commit
used screen coordinates. Update meta_window_get_titlebar_rect function to
return titlebar rectange in screen coordinates.

This also reverts first change in place.c that did not make any sense. x and
y in titlebar_rect always was 0 meaning that we always used CASCADE_FUZZ
value while previously visible border size was used.

https://bugs.launchpad.net/ubuntu/+source/metacity/+bugs/1509031