Replace c style uthash with std::unordered_map<K, V>

[dumganhar]

Now we're using c++11 and have replaced some part of uthash code since v3.0,
but not all code which uses uthash was modified.
The performance of std::unordered_map is good enough, therefore we could safely replace all uthash code with std::unodrdered_map<K, V>, it will be more c++ friendly and readable.

Currently, there are serval modules are using uthash:

TODO LIST:

• FontFNT: Fixed at issue #16661: Replace c style uthash with std::unordered_map<K, V> in CCFontFNT.cpp #16662
• ActionManager
• GLProgram: Just include base/uthash.h, but there isn't anywhere uses it. Fixed at issue #16661: Replace c style uthash with std::unordered_map<K, V> in CCFontFNT.cpp #16662
• Scheduler
• cocos2d_specifics

[stevetranby]

Did you write a performance test (or is there an existing one) that confirms relatively similar performance? I don't doubt it, but confirmation would be nice.

[dumganhar]

@stevetranby , we tested it some years ago. Please refer to

https://docs.google.com/spreadsheets/d/1XolpgYfoWszA2rxnVRCAVS7ILAGiV049o5mpL29cwLs/edit#gid=6

cocos2d::Map<K, V> is using std::unordered_map while cocos2d::Dictionary is using UT_HASH.

Test code could be found at Performance Test project.