add some notes in sse1.c, add test file: test/sse1_test.c
test raid6_sse12_gen_syndrome() in test/sse1_test.c
add mmx algos in sse1_testc, and change sse1_test.c to raid_algos_test.c
delete sse2 algorithms, maybe sse2 can only be run in 64-bit OS