1. clean code;
2. change `cl::Kernel` from unique to shared ptr;
3. `reset` `cl::Program` and `clear` `device_info_` in destroyed of CLRuntime;
4. remove clFlush in destroyed of CLRuntime.

* [LITE][OPENCL] fix OpenCL global static resources. test=develop

* Fix Cxx and light api. test=develop

[LITE][OPENCL] Fix opencl backend: Free opencl resources; Fix AddKernel/GetKernel, program and all opencl kernels (#3344)

* [DONT MERGE] Fix opencl backend.

* [LITE][OPENCL] Fix kernels overlapped when add/get for kernels of mnasnet/yolonano. test=develop

* remove useless. test=develop

* add all image kernels for Get/Add kernel. test=develop

* add all image kernels for Get/Add kernel. test=develop

* fix buffer kernels of opencl. test=develop

* fix release opencl. test=develop

* [LITE][OPENCL][Image] add lws turn &  close cl check when shutdownlog , test=develop

* [LITE][OPENCL][Image] add lws turn &  close cl check when shutdownlog , test=develop

* [LITE][OPENCL][Image] add lws turn &  close cl check when shutdownlog , test=develop

* [LITE][OPENCL][Image] add lws turn &  close cl check when shutdownlog , test=develop

* [LITE][OPENCL][Image] add lws turn &  close cl check when shutdownlog , test=develop

* [LITE][OPENCL] Change fp32 fc to fp16's. test=develop

* fix act in conv3x3opt opencl kernel. test=develop

* [LITE][OPENCL] fix opencl fc kernel. test=develop

* [LITE][OPENCL] add lws for opencl conv image kernel. test=develop