unlzma: speedup, by Pascal Bellard (pascal.bellard AT ads-lu.com)

unlzma: speedup, by Pascal Bellard (pascal.bellard AT ads-lu.com)

LZMA_FAST off: 10% faster and:
function                                             old     new   delta
rc_is_bit_1                                            -      92     +92
rc_do_normalize                                       45      81     +36
rc_update_bit_1                                       25       -     -25
rc_update_bit_0                                       30       -     -30
rc_is_bit_0_helper                                    38       -     -38
rc_get_bit                                            60      17     -43
rc_read                                               48       -     -48
unpack_lzma_stream                                  1768    1517    -251
------------------------------------------------------------------------------
(add/remove: 1/4 grow/shrink: 1/2 up/down: 128/-435)         Total: -307 bytes

LZMA_FAST on: 14% faster and:
unpack_lzma_stream                                  2301    2737    +436
rc_get_bit                                           106       -    -106