Extends the x86_64 Poly1305 authenticator by a function processing four
consecutive Poly1305 blocks in parallel using AVX2 instructions.

For large messages, throughput increases by ~15-45% compared to two
block SSE2:

testing speed of poly1305 (poly1305-simd)
test  0 (   96 byte blocks,   16 bytes per update,   6 updates): 3809514 opers/sec,  365713411 bytes/sec
test  1 (   96 byte blocks,   32 bytes per update,   3 updates): 5973423 opers/sec,  573448627 bytes/sec
test  2 (   96 byte blocks,   96 bytes per update,   1 updates): 9446779 opers/sec,  906890803 bytes/sec
test  3 (  288 byte blocks,   16 bytes per update,  18 updates): 1364814 opers/sec,  393066691 bytes/sec
test  4 (  288 byte blocks,   32 bytes per update,   9 updates): 2045780 opers/sec,  589184697 bytes/sec
test  5 (  288 byte blocks,  288 bytes per update,   1 updates): 3711946 opers/sec, 1069040592 bytes/sec
test  6 ( 1056 byte blocks,   32 bytes per update,  33 updates):  573686 opers/sec,  605812732 bytes/sec
test  7 ( 1056 byte blocks, 1056 bytes per update,   1 updates): 1647802 opers/sec, 1740079440 bytes/sec
test  8 ( 2080 byte blocks,   32 bytes per update,  65 updates):  292970 opers/sec,  609378224 bytes/sec
test  9 ( 2080 byte blocks, 2080 bytes per update,   1 updates):  943229 opers/sec, 1961916528 bytes/sec
test 10 ( 4128 byte blocks, 4128 bytes per update,   1 updates):  494623 opers/sec, 2041804569 bytes/sec
test 11 ( 8224 byte blocks, 8224 bytes per update,   1 updates):  254045 opers/sec, 2089271014 bytes/sec

testing speed of poly1305 (poly1305-simd)
test  0 (   96 byte blocks,   16 bytes per update,   6 updates): 3826224 opers/sec,  367317552 bytes/sec
test  1 (   96 byte blocks,   32 bytes per update,   3 updates): 5948638 opers/sec,  571069267 bytes/sec
test  2 (   96 byte blocks,   96 bytes per update,   1 updates): 9439110 opers/sec,  906154627 bytes/sec
test  3 (  288 byte blocks,   16 bytes per update,  18 updates): 1367756 opers/sec,  393913872 bytes/sec
test  4 (  288 byte blocks,   32 bytes per update,   9 updates): 2056881 opers/sec,  592381958 bytes/sec
test  5 (  288 byte blocks,  288 bytes per update,   1 updates): 3711153 opers/sec, 1068812179 bytes/sec
test  6 ( 1056 byte blocks,   32 bytes per update,  33 updates):  574940 opers/sec,  607136745 bytes/sec
test  7 ( 1056 byte blocks, 1056 bytes per update,   1 updates): 1948830 opers/sec, 2057964585 bytes/sec
test  8 ( 2080 byte blocks,   32 bytes per update,  65 updates):  293308 opers/sec,  610082096 bytes/sec
test  9 ( 2080 byte blocks, 2080 bytes per update,   1 updates): 1235224 opers/sec, 2569267792 bytes/sec
test 10 ( 4128 byte blocks, 4128 bytes per update,   1 updates):  684405 opers/sec, 2825226316 bytes/sec
test 11 ( 8224 byte blocks, 8224 bytes per update,   1 updates):  367101 opers/sec, 3019039446 bytes/sec

Benchmark results from a Core i5-4670T.
Signed-off-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>