FT-556 add snappy compress method
add google snappy to tokuft and the test results as follows:
TOKU_ZLIB_METHOD Time=0.602126s , Ratio=0.33[8416782/25183377]
TOKU_ZLIB_WITHOUT_CHECKSUM_METHOD Time=0.559529s, Ratio=0.33[8415541/25183377]
TOKU_QUICKLZ_METHOD Time=1.079200s, Ratio=0.35[8743582/25183377]
TOKU_LZMA_METHOD Time=3.001958s, Ratio=0.33[8415141/25183377]
TOKU_SNAPPY_METHOD Time=0.171223s, Ratio=0.36[9184871/25183377]