Refactor benchmark result

[info] length           benchmark       us linear runtime
[info]     10 ScalaOldSuffixArray    12.45 =
[info]     10    ScalaSuffixArray     9.68 =
[info]    100 ScalaOldSuffixArray    27.04 =
[info]    100    ScalaSuffixArray    22.39 =
[info]   1000 ScalaOldSuffixArray   236.77 =
[info]   1000    ScalaSuffixArray   274.86 =
[info]   5000 ScalaOldSuffixArray  1321.05 ===
[info]   5000    ScalaSuffixArray  1507.21 ===
[info]  10000 ScalaOldSuffixArray  3811.92 =========
[info]  10000    ScalaSuffixArray  3190.90 ========
[info]  20000 ScalaOldSuffixArray 11686.29 ==============================
[info]  20000    ScalaSuffixArray  6835.64 =================