(w32_char_font_type, w32_encode_char, x_produce_glyphs): Distinguish

(w32_char_font_type, w32_encode_char, x_produce_glyphs): Distinguish
single and multibyte BDF fonts.
(w32_bdf_per_char_metric): New function.
(w32_per_char_metric): Use it.
(x_draw_glyph_string_background): Always draw background for BDF glyphs.

(x_produce_glyphs):  If the distance from the current position to the
next tab stop is less than a canonical character width, use the tab
stop after that.
(x_draw_glyphs): Handle case START and END are out of bounds more carefully.
(x_clear_mouse_face): Block/unblock input.
(x_display_and_set_cursor): Don't show a hollow box cursor for buffers
whose cursor_type is nil.