Update Android port

Update Android port

* INSTALL.android: Describe patches for BoringSSL on ARM.

* src/sfnt.c (sfnt_build_glyph_outline): Remove redundant
multiplication.
(sfnt_prepare_raster): Update offset calculation for changes.
(sfnt_step_edge, sfnt_step_edge_n): Handle bresenham terms.
(sfnt_build_outline_edges): Don't subtract floored xmin, just
xmin.
(sfnt_saturate_short): Make clang generate better code.
(sfnt_fill_span): Stop rounding coordinates.
(sfnt_poly_span): Poly consecutive on transitions all in one go.
(sfnt_lookup_glyph_metrics): Remove redundant multiplication.
(struct sfnt_interpreter): New hooks for debugging.
(sfnt_large_integer_add): New function.
(sfnt_mul_f26dot6_fixed): Round product.
(sfnt_make_interpreter): Remove redundant multiplication.

(CHECK_STACK_ELEMENTS, POP_UNCHECKED, PUSH_UNCHECKED): New
macros.
(MOVE, POP, SWAP, CINDEX, RS, RCVT, LT, LTEQ, GT, GTEQ, EQ, NEQ)
(EVEN, AND, OR, NOT, ADD, SUB, DIV, MUL, ABS, NEG, FLOOR, CEILING)
(GETINFO, ROLL, _MAX, _MIN, ROUND, NROUND, GC, MD): Don't check
SP redundantly, especially when pushing an element right after
popping one.
(sfnt_move_glyph_zone): Don't touch points by passing NULL as
flags.
(sfnt_direct_move_zp2): Touch P in the directions of the
movement.
(sfnt_interpret_scfs): Fix coding style.
(sfnt_interpret_simple_glyph): Don't round Y coordinates.
(sfnt_test_span, sfnt_test_edges, sfnt_debug_edges, sfnt_test_edge)
(sfnt_x_raster, sfnt_test_raster, rcvt_test_args)
(deltac1_test_args, deltac2_test_args, deltac3_test_args)
(roll_1_test_args, sfnt_run_hook, sfnt_identify_instruction)
(sfnt_verbose, main): Improve debug code and tests.

* src/sfnt.h (struct sfnt_edge): Add bresenham terms.