Move genconfig/gencode to ../cmake/memcached

be moved back when ep-engine is being built by CMake

Change-Id: If7aaca45ec63e0b2aa9cc332873865943758d745
Use implementations from platform lib

Change-Id: Ic92b3960d73c4f6c89e43491031d386f41754b46
Use common cJSON

Change-Id: Ic145eb819a3273b862f082bdcd2ea406e9909966
foo

Change-Id: Id5ccc1331e9d662356e6de78b17c7fdb7983dbee