port nms extension from maskrcnn-benchmark (open-mmlab#469)

* port nms extension from maskrcnn-benchmark

* fix linting error

Author: hellock

.gitignore

@@ -104,7 +104,7 @@ venv.bak/
 .mypy_cache/
 
 # cython generated cpp
-mmdet/ops/nms/*.cpp
+mmdet/ops/nms/src/soft_nms_cpu.cpp
 mmdet/version.py
 data
 .vscode

compile.sh

@@ -18,8 +18,10 @@ $PYTHON setup.py build_ext --inplace
 
 echo "Building nms op..."
 cd ../nms
-make clean
-make PYTHON=${PYTHON}
+if [ -d "build" ]; then
+    rm -r build
+fi
+$PYTHON setup.py build_ext --inplace
 
 echo "Building dcn..."
 cd ../dcn