internals: core/router/api_builder_benchmark_test.go: replace the strings.Builder(go 1.10+) with the bytes.Buffer, it is a test so we are ok let it build and run for go1.10- as well
internals: core/router/api_builder_benchmark_test.go: replace the strings.Builder(go 1.10+) with the bytes.Buffer, it is a test so we are ok let it build and run for go1.10- as well

Former-commit-id: a531db90fe02fd327e12ecc20128090e18b3dbcb
kataras/iris,kataras/iris,kataras/gapi,kataras/iris,kataras/iris,kataras/gapi