speedtest: Ask the user to increase duration with empty result. (#3875)
speedtest: Ask the user to increase duration with empty result. (#3875)

Sometimes, with slow machines, speedtest will not able to accomplish
any PUT/GET operations though no errors is met. In that case, this
commit will show an adequate error message asking the user to increase
the --duration flag.
balamurugana/mc,vadmeste/mc,krisis/mc,minio/mc,balamurugana/mc,vadmeste/mc,krisis/mc,minio/mc