ddtrace/tracer: don't use UTC() when getting time (#1134)

ddtrace/tracer/time.go

@@ -3,13 +3,14 @@
 // This product includes software developed at Datadog (https://www.datadoghq.com/).
 // Copyright 2016 Datadog, Inc.
 
+//go:build !windows
 // +build !windows
 
 package tracer
 
 import "time"
 
-// now returns current UTC time in nanos.
+// now returns the current UNIX time in nanoseconds, as computed by Time.UnixNano().
 func now() int64 {
-	return time.Now().UTC().UnixNano()
+	return time.Now().UnixNano()
 }

ddtrace/tracer/time_windows.go

@@ -23,7 +23,7 @@ func highPrecisionNow() int64 {
 }
 
 func lowPrecisionNow() int64 {
-	return time.Now().UTC().UnixNano()
+	return time.Now().UnixNano()
 }
 
 var now func() int64