Fix issue 4961 (#5025)

Signed-off-by: GuoHuiPeng <1205504832@qq.com>

tree.go

@@ -284,6 +284,8 @@ func (t *Tree) addseg(segments []string, route interface{}, wildcards []string,
 
 // Match router to runObject & params
 func (t *Tree) Match(pattern string, ctx *context.Context) (runObject interface{}) {
+        // fix issue 4961, deal with "./ ../ //"
+        pattern = path.Clean(pattern)
 	if len(pattern) == 0 || pattern[0] != '/' {
 		return nil
 	}