Upgrade vitess to v1.2.1

[kuba--]

Signed-off-by: kuba-- [email protected]

[kuba--]

After upgrading vitess (and tag it v.1.2.1) I've just run:
GO111MODULE=ON go build ./...

[erizocosmico]

CI is failing

[kuba--]

I'm off, but something with logging on vitess has been changed. I'll investigate tonight.

[erizocosmico]

Don't worry, there's no hurry with this. Enjoy the day off!

[kuba--]

It's panics because we replaced glog by logrus.
glog in init function defines flags:
flag.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr")

If we replaced glog by logrus then stderrthreshold is not defined, but is required by logutil package (logutil/level.go):

func init() {
	threshold := flag.Lookup("stderrthreshold")
	if threshold == nil {
		panic("the logging module doesn't specify a stderrthreshold flag")
	}
//...