Serpent: faster S-box implementation

* cipher/serpent.c (SBOX0, SBOX1, SBOX2, SBOX3, SBOX4, SBOX5, SBOX6)
(SBOX7, SBOX0_INVERSE, SBOX1_INVERSE, SBOX2_INVERSE, SBOX3_INVERSE)
(SBOX4_INVERSE, SBOX5_INVERSE, SBOX6_INVERSE, SBOX7_INVERSE): Replace
with new definitions.
--

These new S-box definitions are from paper:
 D. A. Osvik, “Speeding up Serpent,” in Third AES Candidate Conference,
 (New York, New York, USA), p. 317–329, National Institute of Standards and
 Technology, 2000. Available at http://www.ii.uib.no/~osvik/pub/aes3.ps.gz

Although these were optimized for two-operand instructions on i386 and for
old Pentium-1 processors, they are slightly faster on current processors
on i386 and x86-64. On ARM, the performance of these S-boxes is about the
same as with the old S-boxes.

new vs old speed ratios (AMD K10, x86-64):
                 ECB/Stream         CBC             CFB             OFB             CTR
              --------------- --------------- --------------- --------------- ---------------
 SERPENT128     1.06x   1.02x   1.06x   1.02x   1.06x   1.06x   1.06x   1.05x   1.07x   1.07x

new vs old speed ratios (Intel Atom, i486):
                 ECB/Stream         CBC             CFB             OFB             CTR
              --------------- --------------- --------------- --------------- ---------------
 SERPENT128     1.12x   1.15x   1.12x   1.15x   1.13x   1.11x   1.12x   1.12x   1.12x   1.13x

new vs old speed ratios (ARM Cortex A8):
                 ECB/Stream         CBC             CFB             OFB             CTR
              --------------- --------------- --------------- --------------- ---------------
 SERPENT128     1.04x   1.02x   1.02x   0.99x   1.02x   1.02x   1.03x   1.03x   1.01x   1.01x

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>

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