reflect: remove a double negative, use the rtype.pointers method for clarity

Change-Id: Ia24e9f0da1622cededa17b2c54ff9e4bb80cf946
Reviewed-on: https://go-review.googlesource.com/1633Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/reflect/type.go

@@ -1908,7 +1908,7 @@ func (bv *bitVector) append2(bits uint8) {
 
 func addTypeBits(bv *bitVector, offset *uintptr, t *rtype) {
 	*offset = align(*offset, uintptr(t.align))
-	if t.kind&kindNoPointers != 0 {
+	if !t.pointers() {
 		*offset += t.size
 		return
 	}