Update Android port

Update Android port

* src/androidterm.c (android_draw_image_glyph_string): Restore
potentially clobbered GC clipping.
* src/sfnt.c (sfnt_large_integer_add, sfnt_multiply_divide_round)
(sfnt_mul_fixed_round): New functions.
(sfnt_build_glyph_outline): Take unscaled glyph metrics.
(sfnt_prepare_raster, sfnt_vary_simple_glyph)
(sfnt_vary_compound_glyph, sfnt_vary_interpreter): Use rounding
multiplication to scale deltas.
(main): Adjust tests.
* src/sfntfont.c (sfntfont_get_glyph_outline)
(sfntfont_probe_widths, sfntfont_open, sfntfont_measure_pcm)
(sfntfont_draw): More minor fixes to variable fonts.