use go 1.12

Signed-off-by: hongming <talonwan@yunify.com>

vendor/github.com/lucas-clemente/quic-go/internal/congestion/clock.go

@@ -0,0 +1,18 @@
+package congestion
+
+import "time"
+
+// A Clock returns the current time
+type Clock interface {
+	Now() time.Time
+}
+
+// DefaultClock implements the Clock interface using the Go stdlib clock.
+type DefaultClock struct{}
+
+var _ Clock = DefaultClock{}
+
+// Now gets the current time
+func (DefaultClock) Now() time.Time {
+	return time.Now()
+}