Update Android port

Update Android port

* src/sfnt.c (sfnt_table_names): Add fvar, gvar, cvar.
(sfnt_read_maxp_table): Call xmalloc, not malloc.
(sfnt_read_simple_glyph): Avoid use-after-free if simple is
invalid.
(sfnt_fill_span): Fix max coverage.
(sfnt_normalize_vector): Fail if magnitude is zero.
(sfnt_measure_distance): Fix opcode order.
(sfnt_dot_fix_14): Fix implementation.
(struct sfnt_variation_axis, struct sfnt_instance)
(struct sfnt_fvar_table, struct sfnt_gvar_table)
(sfnt_read_fvar_table, sfnt_read_gvar_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_points, sfnt_read_packed_deltas)
(sfnt_compute_tuple_scale, sfnt_infer_deltas_1, sfnt_infer_deltas)
(sfnt_vary_glyph): Add WIP variation glyph implementation.
* src/sfnt.h (enum sfnt_table, struct sfnt_simple_glyph):
Likewise.