* read-only modification of cppDesc, test=develop

* update io.cc, test=develop

* fix the code style, test=develop

* update desc interfaces, test=develop

* update desc interfaces, test=develop

* update compatible_pb.cc, test=develop

* fix build errors, test=develop

* remove the fstream to shrink the size of library, test=develop

* add flatbuffers, test=develop

* fix cmake codes, test=develop

add cuda kernel.

abs, tanh, elementwise_sub

* add gpu kernel mul pool relu scale softmax dropout bilinear_interp and can run in tx2

* rm GREATER_EQUAL

* paddle lite cuda init
can run model with leaky_relu

* add the missing file.
test=develop