Fix display of cursor at end of empty lines

Fix display of cursor at end of empty lines

* src/xdisp.c (normal_char_ascent_descent): Accept additional
argument: the character to use for metrics in case the font
declares too large ascent and descent values.  Add 1 pixel to
ascent and descent values.
(normal_char_height): Accept additional argument: the character to
use for metrics in case the font declares too large height value.
Call normal_char_ascent_descent instead of doing calculations for
a different default character.
(estimate_mode_line_height, handle_single_display_spec)
(calc_pixel_width_or_height, produce_stretch_glyph)
(calc_line_height_property, produce_glyphless_glyph): All callers
changed.
(append_space_for_newline): Make sure the space glyph produced at
end of line has correct ascent and descent values, and the glyph
row has correct height, even when it's empty.