(mac_define_frame_cursor): Don't change pointer shape

(mac_define_frame_cursor): Don't change pointer shape
for unfocused frame.
(x_raise_frame): Call BringToFront instead of SelectWindow.
(x_lower_frame): Use NULL instead of nil.
(x_make_frame_visible): Don't call SelectWindow.
(XTread_socket): Increment handling_signal at the start, decrement
it at the end.
[USE_CG_TEXT_DRAWING] (init_cg_text_anti_aliasing_threshold): Use
CFPreferencesGetAppIntegerValue instead of Fmac_get_preference.