Add new font backend drivers for text shaping by HarfBuzz

Add new font backend drivers for text shaping by HarfBuzz

* etc/NEWS: Mention new font backend drivers xfthb and ftcrhb.

* src/font.h [HAVE_HARFBUZZ]: Include hb.h.
(struct font_driver) [HAVE_HARFBUZZ]: New members begin_hb_font and
end_hb_font.
(ftfont_match, ftfont_list): Remove externs.
(ftfont_match2, ftfont_list2):
(fthbfont_combining_capability, fthbfont_begin_hb_font)
(fthbfont_shape) [HAVE_HARFBUZZ]:
(xfthbfont_driver) [HAVE_XFT && HAVE_HARFBUZZ]:
(ftcrhbfont_driver) [USE_CAIRO && HAVE_HARFBUZZ]: Add externs.

* src/ftcrfont.c (ftcrfont_list): Use ftfont_list2.
(ftcrfont_match): Use ftfont_match2.
(ftcrfont_open): Get font type from entity.
(ftcrfont_open) [HAVE_HARFBUZZ]: Use HarfBuzz version of driver if specified.
(ftcrfont_shape) [HAVE_HARFBUZZ]: Make shaping fail.
(ftcrhbfont_list, ftcrhbfont_match)
(ftcrhbfont_begin_hb_font) [HAVE_HARFBUZZ]: New functions.
(ftcrhbfont_driver) [HAVE_HARFBUZZ]: New variable.
(syms_of_ftcrfont_for_pdumper) [HAVE_HARFBUZZ]: Initialize and register it.
(syms_of_ftcrfont) [HAVE_HARFBUZZ]: New symbol Qftcrhb.

* src/ftfont.c: Include math.h for lround.
(fthbfont_driver) [HAVE_HARFBUZZ]: New variable.
(ftfont_get_hb_font) [HAVE_HARFBUZZ]: Remove function.
(ftfont_list, ftfont_match): Make static.
(ftfont_list2, ftfont_match2): New functions.
(ftfont_open2) [HAVE_HARFBUZZ]: Use HarfBuzz version of driver if specified.
(ftfont_open): Get font type from entity.
(ftfont_shape, ftfont_combining_capability, ftfont_driver) [HAVE_HARFBUZZ]:
Move HarfBuzz specific part from here ...
(fthbfont_shape, fthbfont_combining_capability)
(fthbfont_driver) [HAVE_HARFBUZZ]: ... to here.   New functions and variable.
(fthbfont_begin_hb_font) [HAVE_HARFBUZZ]: New function.
(fthbfont_shape_by_hb) [HAVE_HARFBUZZ]: Rename from ftfont_shape_by_hb.
Don't take FreeType specific arguments ft_face and matrix.  Use begin_hb_font
and end_hb_font font driver functions.  Use text_extents font driver functions
instead of ftfont_glyph_metrics.
(syms_of_ftfont) [HAVE_HARFBUZZ]: New symbol Qfreetypehb.
(syms_of_ftfont_for_pdumper) [HAVE_HARFBUZZ]: Initialize and register
fthbfont_drivert.

* src/ftxfont.c (ftxfont_list): Use ftfont_list2.
(ftxfont_match): Use ftfont_match2.
(ftxfont_driver) [HAVE_HARFBUZZ]: Don't initialize shape member explicitly.

* src/xfns.c (Fx_create_frame) [USE_CAIRO && HAVE_HARFBUZZ]:
(Fx_create_frame) [HAVE_XFT && HAVE_HARFBUZZ]: Register HarfBuzz versions of
font drivers.

* src/xftfont.c (xftfont_list): Use ftfont_list2.
(xftfont_match): Use ftfont_match2.
(xftfont_open): Get font type from entity.
(xftfont_open) [HAVE_HARFBUZZ]: Use HarfBuzz version of driver if specified.
(xftfont_shape) [HAVE_HARFBUZZ]: Make shaping fail.
(xfthbfont_list, xfthbfont_match, xfthbfont_begin_hb_font)
(xfthbfont_end_hb_font) [HAVE_HARFBUZZ]: New functions.
(xftfont_driver) [HAVE_HARFBUZZ]: Don't initialize shape member explicitly.
(xfthbfont_driver) [HAVE_HARFBUZZ]: New variable.
(syms_of_xftfont_for_pdumper) [HAVE_HARFBUZZ]: Initialize and register it.
(syms_of_xftfont) [HAVE_HARFBUZZ]: New symbol Qxfthb.