fix tests in package helpers/testsuite with Go 1.8
fix tests in package helpers/testsuite with Go 1.8

cloudflare/cfssl,geligaoli/cfssl,geligaoli/cfssl,drcapulet/cfssl,drcapulet/cfssl,cloudflare/cfssl,cloudflare/cfssl,drcapulet/cfssl,geligaoli/cfssl,drcapulet/cfssl,geligaoli/cfssl,drcapulet/cfssl,geligaoli/cfssl,cloudflare/cfssl