Fix Xcode build.

Move the make_directory command to the main target, so that CMAKE_CFG_INTDIR
will get expanded by the build tool.

Modules/FindCUDA.cmake

@@ -1027,6 +1027,8 @@ macro(CUDA_WRAP_SRCS cuda_target format generated_files)
         ${main_dep}
         DEPENDS ${CUDA_NVCC_DEPEND}
         DEPENDS ${custom_target_script}
+        # Make sure the output directory exists before trying to write to it.
+        COMMAND ${CMAKE_COMMAND} -E make_directory "${generated_file_path}"
         COMMAND ${CMAKE_COMMAND} ARGS
           -D verbose:BOOL=${verbose_output}
           ${ccbin_flags}

Modules/FindCUDA/run_nvcc.cmake

@@ -150,12 +150,6 @@ cuda_execute_process(
   COMMAND "${CMAKE_COMMAND}" -E remove "${generated_file}"
   )
 
-# Make sure the output directory is present
-cuda_execute_process(
-  "Creating output directory: ${generated_file_path}"
-  COMMAND "${CMAKE_COMMAND}" -E make_directory "${generated_file_path}"
-  )
-
 # Generate the dependency file
 cuda_execute_process(
   "Generating dependency file: ${NVCC_generated_dependency_file}"