time bug: darwin, linux return microseconds not nanoseconds

R=r
DELTA=2  (0 added, 0 deleted, 2 changed)
OCL=15626
CL=15641

src/syscall/time_amd64_darwin.go

@@ -15,5 +15,5 @@ export func gettimeofday() (sec, nsec, errno int64) {
 	if err != 0 {
 		return 0, 0, err
 	}
-	return r1, r2, 0
+	return r1, r2*1000, 0
 }

src/syscall/time_amd64_linux.go

@@ -15,5 +15,5 @@ export func gettimeofday() (sec, nsec, errno int64) {
 	if err != 0 {
 		return 0, 0, err
 	}
-	return tv[0], tv[1], 0
+	return tv[0], tv[1]*1000, 0
 }