BenchmarkCompareStringEqual               10.4          7.33          -29.52%
BenchmarkCompareStringIdentical           3.99          3.67          -8.02%
BenchmarkCompareStringSameLength          9.80          6.84          -30.20%
BenchmarkCompareStringDifferentLength     1.09          0.95          -12.84%
BenchmarkCompareStringBigUnaligned        75220         76071         +1.13%
BenchmarkCompareStringBig                 69843         74746         +7.02%

LGTM=bradfitz, josharian
R=golang-codereviews, bradfitz, josharian, dave, khr
CC=golang-codereviews
https://golang.org/cl/105280044