Use `CMAKE_CURRENT_SOURCE_DIR` instead of `CMAKE_SOURCE_DIR` (#1333)

use CMAKE_CURRENT_SOURCE_DIR instead of CMAKE_SOURCE_DIR
Signed-off-by: Kenichi Maehashi <webmaster@kenichimaehashi.com>

transformer_engine/common/CMakeLists.txt

@@ -30,14 +30,14 @@ endif()
 
 # cuDNN frontend API
 set(CUDNN_FRONTEND_INCLUDE_DIR
-    "${CMAKE_SOURCE_DIR}/../../3rdparty/cudnn-frontend/include")
+    "${CMAKE_CURRENT_SOURCE_DIR}/../../3rdparty/cudnn-frontend/include")
 if(NOT EXISTS "${CUDNN_FRONTEND_INCLUDE_DIR}")
     message(FATAL_ERROR
-            "Could not find cuDNN frontend API. "
+            "Could not find cuDNN frontend API at ${CUDNN_FRONTEND_INCLUDE_DIR}. "
             "Try running 'git submodule update --init --recursive' "
             "within the Transformer Engine source.")
 endif()
-include(${CMAKE_SOURCE_DIR}/../../3rdparty/cudnn-frontend/cmake/cuDNN.cmake)
+include(${CMAKE_CURRENT_SOURCE_DIR}/../../3rdparty/cudnn-frontend/cmake/cuDNN.cmake)
 
 # Python
 find_package(Python COMPONENTS Interpreter Development.Module REQUIRED)