GitLab

	* w32term.h (GUISTR, GUI_ENCODE_FILE, GUI_ENCODE_SYSTEM, GUI_FN)
	(GUI_SDATA, guichar_t): Macros to abstract out differences between
	NTGUI_UNICODE and !NTGUI_UNICODE builds, some moved out of
	w32fns.c.

	* w32term.c (construct_drag_n_drop): Use the above macros to make
	drag-and-drop work for non-ASCII filenames in cygw32 builds.

	* w32fns.c (x_set_name, x_set_title): Use the above macros to
	properly display non-ASCII frame titles in cygw32 builds.

	* w32fns.c (Fw32_shell_execute): Use the above macros to properly
	call ShellExecute in cygw32 builds.

	* w32fn.c (Fx_file_dialog): Use the above macros to simplify the
	common file dialog code.

	* w32fns.c (Ffile_system_info): Remove from cygw32 builds, which
	can just use du like other systems.

	* coding.c (from_unicode_buffer): Declare.
	* coding.c (from_unicode_buffer): Implement.