Improve pybind11 message (pytorch#11640)

Summary:
Improving the message based on pytorch#11570
Pull Request resolved: pytorch#11640

Differential Revision: D10033383

Pulled By: orionr

fbshipit-source-id: 0cdcdbe0582d896283a12970aebe771efa390dd2

cmake/Dependencies.cmake

@@ -402,13 +402,15 @@ find_package(pybind11 CONFIG)
 if((DEFINED pybind11_DIR) AND pybind11_DIR)
   get_target_property(pybind11_INCLUDE_DIRS pybind11::pybind11 INTERFACE_INCLUDE_DIRECTORIES)
 else()
-  message("pybind11 config not found. Fallback to legacy find.")
   find_package(pybind11)
 endif()
 
 if(pybind11_FOUND)
+    message(STATUS "System pybind11 found")
+    message(STATUS "pybind11l include dirs: " ${pybind11_INCLUDE_DIRS})
     include_directories(SYSTEM ${pybind11_INCLUDE_DIRS})
 else()
+    message(STATUS "Using third_party/pybind11.")
     include_directories(SYSTEM ${CMAKE_CURRENT_LIST_DIR}/../third_party/pybind11/include)
 endif()