compiler/natives/src/time: Update now signature for monotonic time.

Fixes:

	$GOROOT/src/time/time.go:1049:21: cannot initialize 3 variables with 2 values
	$GOROOT/src/time/zoneinfo_read.go:202:15: cannot initialize 3 variables with 2 values

compiler/natives/src/time/time.go

@@ -42,9 +42,10 @@ func runtimeNano() int64 {
 	return js.Global.Get("Date").New().Call("getTime").Int64() * int64(Millisecond)
 }
 
-func now() (sec int64, nsec int32) {
+func now() (sec int64, nsec int32, mono int64) {
+	// TODO: Use mono if needed/possible.
 	n := runtimeNano()
-	return n / int64(Second), int32(n % int64(Second))
+	return n / int64(Second), int32(n % int64(Second)), 0
 }
 
 func Sleep(d Duration) {