querySkuDetails() did not make load skuDetails when request skuList.size()%20 == 0

[andrii-bakulin]

When do querySkuDetails with list of 20, 40, 60 items it not do sync-query.

In this code need to close block after selected lines:
https://github.com/cocos2d-x/plugin-x/blob/v4-develop/plugins/googleplay/proj.android/src/org/cocos2dx/plugin/util/IabHelper.java#L927-L932

and after that block should always execute:

https://github.com/cocos2d-x/plugin-x/blob/v4-develop/plugins/googleplay/proj.android/src/org/cocos2dx/plugin/util/IabHelper.java#L934-L960