Fix missing mkl-dnn include paths (pytorch#117492)

Fixes pytorch#91968 and pytorch#100960
This commit fixes missing  include paths by linking `caffe2_pybind11_state_gpu` against `caffe2::mkldnn`
Pull Request resolved: pytorch#117492
Approved by: https://github.com/ezyang

caffe2/CMakeLists.txt

@@ -1971,6 +1971,9 @@ if(BUILD_PYTHON)
     target_include_directories(caffe2_pybind11_state_gpu PRIVATE ${Caffe2_CPU_INCLUDE})
     target_link_libraries(caffe2_pybind11_state_gpu PRIVATE
         torch_library python::python pybind::pybind11)
+    if(USE_MKLDNN)
+        target_link_libraries(caffe2_pybind11_state_gpu PRIVATE caffe2::mkldnn)
+    endif()
     if(WIN32)
       target_link_libraries(caffe2_pybind11_state_gpu PRIVATE onnx_proto)
     endif(WIN32)