Update Android port

Update Android port

* src/sfnt.c (sfnt_table_names): Add avar.
(sfnt_read_glyph): Clear distortion fields.
(sfnt_build_glyph_outline): Calculate the outline origin point.
(sfnt_prepare_raster): Apply the origin point to the X axis
offset.
(sfnt_scale_metrics_to_pixel_size): New function.
(sfnt_build_instructed_outline): Use instructed origin phantom
point to determine the outline origin.
(sfnt_compute_phantom_points): Apply origin and advance
distortion.
(struct sfnt_variation_axis, struct sfnt_instance)
(struct sfnt_fvar_table, sfnt_read_fvar_table)
(struct sfnt_gvar_table, sfnt_read_gvar_table)
(sfnt_read_avar_table, struct sfnt_blend, sfnt_init_blend)
(sfnt_free_blend, sfnt_normalize_blend, struct sfnt_tuple_header)
(struct sfnt_gvar_glyph_header, sfnt_read_packed_deltas)
(sfnt_compute_tuple_scale, sfnt_read_cvar_table)
(sfnt_infer_deltas_1, sfnt_vary_simple_glyph, sfnt_infer_deltas)
(sfnt_vary_glyph, sfnt_vary_compound_glyph)
(sfnt_vary_interpreter): New functions.  Add structs to
sfntfont.h.
(struct sfnt_test_dcontext, sfnt_test_get_glyph, main): Test
distortable font handling.

* src/sfnt.h (SFNT_ENABLE_HINTING):
(enum sfnt_table):
(struct sfnt_glyph):
(struct sfnt_glyph_outline):
(struct sfnt_raster):
(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):
(struct sfnt_variation_axis):
(struct sfnt_instance):
(struct sfnt_fvar_table):
(struct sfnt_short_frac_correspondence):
(struct sfnt_short_frac_segment):
(struct sfnt_avar_table):
(struct sfnt_tuple_variation):
(struct sfnt_cvar_table):
(struct sfnt_gvar_table):
(struct sfnt_blend):
(struct sfnt_metrics_distortion):
(PROTOTYPE): Update prototypes.

* src/sfntfont.c (sfntfont_get_glyph_outline):
(sfntfont_measure_pcm): Adjust calls.