reflect/type.go: add special case judgement before scan T's and V's methods

This change can avoid redundant linear scanning when the number of T's methods is less than the number of V's methods, which  can enhance the efficiency while judging whether a type implements a interface.

src/reflect/type.go

@@ -1498,6 +1498,9 @@ func implements(T, V *rtype) bool {
 	// See also ../runtime/iface.go.
 	if V.Kind() == Interface {
 		v := (*interfaceType)(unsafe.Pointer(V))
+		if len(v.methods) < len(t.methods) {
+			return false
+		}
 		i := 0
 		for j := 0; j < len(v.methods); j++ {
 			tm := &t.methods[i]