add cuda kernel.

abs, tanh, elementwise_sub

* fix format, test=develop

* add some op infershape implement, test=develop

 fix sequence_pool bug

* [LITE][OPENCL] Add ImageFree for Free in memory. test=develop

* add initialize for cl_use_image2d_ when use buffer. test=develop

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

* fix instanceNorm of opencl. test=develop

* add more info about cl device info. test=develop

* [LITE][OPENCL][Image] mv kernel init gws lws into prepare for run, test=develop

* [LITE][OPENCL][Image] shut down profile, test=develop

* [LITE][OPENCL][Image] move log ahead, test=develop

fix cv v8 build error, test=develop

test=develop

* [LITE][OPENCL] enhance elemul, fix reshape for opencl. test=develop

* comment loop test for pad2 opencl kernel. test=develop

* [LITE][PROFILE] add sequnce statics for precision profiler. test=develop

* rename elementwise_sub_grad, test=develop

* rename Grad to GRAD, test=develop

* deal with case that Y@GRAD is empty, test=develop

* fix ci for test_mobilenetv1/v2. test=develop

* [OPENCL][CI] add test_mobilenetv1/v2 for opencl ci. test=develop

* [LITE][OPENCL][Image]optimise conv2d 5x5 7x7,test=develop

* [LITE][OPENCL][Image]optimise conv2d 5x5 7x7,test=develop

* [LITE][OPENCL][Image]optimise conv2d 5x5 7x7,test=develop

* [LITE][OPENCL] comment vlog for opencl kernel. test=develop

* fxi ff, test=develop

* delete bgr_flip, test=develop

* Ehance mobilenetv1/v2, add std_dev computation. test=develop

* Ehance cxx mobile_light demo, add std_dev computation. test=develop

* rm grad code

* [LITE][OPENCL] clean code for opencl. test=develop

* [LITE][PROFILER] Enhance Precision Profiler. test=develop

* delete useless var in profiler. test=develop

* add ocl header. test=develop

* rm grad code

* add mul_grad, test=develop

* add strip lib in ios

* add strip lib in ios test=develop