Redo the whole window offsets and coordinate translation for X.
* frame.h (struct frame): Remove x_pixels_diff, y_pixels_diff.
* w32fns.c (x_real_positions): Remove setting of x_pixels_diff,
y_pixels_diff.
* xfns.c (x_real_pos_and_offsets): New function, basically the code
from x_real_positions.
(x_real_positions): Call x_real_pos_and_offsets.
(x_relative_mouse_position): Use XTranslateCoordinates instead of
OUTER_TO_INNER_DIFF macros.
(Fx_frame_geometry): Get offsets with x_real_pos_and_offsets,
border from window attributes. Adjust tool bar and menu widths.
* xmenu.c (create_and_show_popup_menu): Use XTranslateCoordinates
instead of OUTER_TO_INNER_DIFF macros.
* xterm.h (struct x_output): Remove x_pixels_outer_diff,
y_pixels_outer_diff, FRAME_OUTER_TO_INNER_DIFF_X,
FRAME_OUTER_TO_INNER_DIFF_Y. Declare x_real_pos_and_offsets.