Fixed a build error.

fusetesting/stat.go

@@ -55,12 +55,6 @@ func mtimeIs(c interface{}, expected time.Time) error {
 	return nil
 }
 
-// Extract the mtime from the result of os.FileInfo.Sys(), in a
-// platform-specific way. If not supported on this platform, return !ok.
-//
-// Defined in stat_darwin.go, etc.
-func extractMtime(sys interface{}) (mtime time.Time, ok bool)
-
 // Match os.FileInfo values that specify a file birth time equal to the given
 // time. On platforms where there is no birth time available, match all
 // os.FileInfo values.