Update Android port

Update Android port

* configure.ac: Add support for HarfBuzz on Android.
* java/INSTALL: Document where to get Emacs with HarfBuzz.
* lisp/subr.el (overriding-text-conversion-style, y-or-n-p):
Correctly set text conversion style if y-or-n-p is called inside
the minibuffer.
* src/sfnt.c (sfnt_read_cmap_format_8)
(sfnt_read_cmap_format_12): Fix typos.
(sfnt_read_24, sfnt_read_cmap_format_14): New function.
(sfnt_read_cmap_table_1, sfnt_read_cmap_table): Handle format 14
cmap tables.
(sfnt_read_default_uvs_table, sfnt_read_nondefault_uvs_table)
(sfnt_compare_table_offsets, sfnt_create_uvs_context)
(sfnt_free_uvs_context, sfnt_compare_uvs_mapping)
(sfnt_variation_glyph_for_char, sfnt_map_table, sfnt_unmap_table)
(sfnt_read_table, sfnt_test_uvs): New functions.
(main): Add UVS tests.
* src/sfnt.h (struct sfnt_cmap_format_14)
(struct sfnt_variation_selector_record)
(struct sfnt_default_uvs_table, struct sfnt_unicode_value_range)
(struct sfnt_nondefault_uvs_table, struct sfnt_uvs_mapping)
(struct sfnt_mapped_variation_selector_record)
(struct sfnt_table_offset_rec, struct sfnt_uvs_context)
(struct sfnt_mapped_table): New structures.  Update prototypes.
* src/sfntfont-android.c (android_sfntfont_driver): Register
HarfBuzz callbacks where required.
* src/sfntfont.c (sfntfont_select_cmap): Look for a format 14
table.  Save it in new arg FORMAT14.
(sfntfont_read_cmap): Adjust accordingly.
(struct sfnt_font_info): New field `uvs'.  New fields `hb_font',
`fd' and `directory'.
(sfntfont_open): Open uvs context.  Under HarfBuzz, don't close
the fd or subtable, but save them in the font info instead.
(sfntfont_close): Free UVS context.  Close font fd and table
directory and HarfBuzz font.
(sfntfont_draw): Handle case where s->padding_p.
(sfntfont_get_variation_glyphs): New function.
(sfntfont_unmap_blob, sfntfont_get_font_table)
(sfntfont_begin_hb_font): New functions.
* src/sfntfont.h: Update prototypes.
* src/textconv.c (Fset_text_conversion_style): Fix doc string.