Cherry pick v1.7 into master

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/option.go

@@ -154,10 +154,19 @@ func FinishTime(t time.Time) FinishOption {
 	}
 }
 
-// WithError adds the given error to the span before marking it as finished. If it is
-// nil it will be disregarded.
+// WithError marks the span as having had an error. It uses the information from
+// err to set tags such as the error message, error type and stack trace.
 func WithError(err error) FinishOption {
 	return func(cfg *ddtrace.FinishConfig) {
 		cfg.Error = err
 	}
 }
+
+// NoDebugStack prevents any error presented using the WithError finishing option
+// from generating a stack trace. This is useful in situations where errors are frequent
+// and performance is critical.
+func NoDebugStack() FinishOption {
+	return func(cfg *ddtrace.FinishConfig) {
+		cfg.NoDebugStack = true
+	}
+}