Correct monotonic times before use.

The monotonic times are time.Durations, which need to be adjusted before
they can be used as Roughtime UTC milliseconds.

Change-Id: I2bf8a7f6067b3e522350c47a1cb1d13f63b70b32

go/client/client.go

diff --git a/go/client/client.go b/go/client/client.go
index 7938e72..004f829 100644
--- a/go/client/client.go
+++ b/go/client/client.go
@@ -201,6 +201,7 @@
 // alignTo updates s so that its base value matches that from reference.
 func (s *timeSample) alignTo(reference *timeSample) {
 	delta := new(big.Int).Sub(s.base, reference.base)
+	delta.Div(delta, big.NewInt(int64(time.Microsecond)))
 	s.base.Sub(s.base, delta)
 	s.min.Sub(s.min, delta)
 	s.max.Sub(s.max, delta)