Created by: NHZlX

• Fix TensorRT detection bug

1. Add new search path for TensorRT at tensorrt.cmake
2. Add better debug message
3. Fix the bug of detection of TensorRT version

In NVIDIA official docker image, TensorRT headers are located at /usr/include/x86_64-linux-gnu and TensorRT libraries are located at /usr/lib/x86_64-linux-gnu, so using -DTENSORRT_ROOT will fail to detect TensorRT.

There is no debug/warning message to tell developer that TensorRT is failed to be detected.

In later version of TensorRT (e.g. v6), NV_TENSORRT_MAJOR is defined at NvInferVersion.h instead of NvInfer.h, so add compatibility fix.

• Fix TensorRT variables in CMake

1. Replace ${TENSORRT_ROOT}/include with ${TENSORRT_INCLUDE_DIR}
2. Replace ${TENSORRT_ROOT}/lib with ${TENSORRT_LIBRARY}

Manually type path may locate incorrect path of TensorRT. Use the paths detected by system instead.

• Fix TensorRT library path

1. Add new variable - ${TENSORRT_LIBRARY_DIR}
2. Fix TensorRT library path

inference_lib.cmake and setup.py.in need the path of TensorRT library instead of the file of TensorRT library, so add new variable to fix it.

• Add more general search rule for TensoRT

Let system detect architecture instead of manually assign it, so replace x86_64-linux-gnu with ${CMAKE_LIBRARY_ARCHITECTURE}.

• Add more general search rule for TensorRT

Remove duplicate search rules for TensorRT libraries. Use ${TENSORRT_LIBRARY_DIR} to get full path of libnvinfer.so

test=release/1.6