Add `#pragma once` to CUDA foreach headers (#58209)

Summary:
Per the title, adding `#pragma once` to cuda headers related to foreach functions.

cc: ptrblck

Pull Request resolved: https://github.com/pytorch/pytorch/pull/58209

Reviewed By: ailzhang

Differential Revision: D28558620

Pulled By: ngimel

fbshipit-source-id: 195f68435999eb7409ba904daf6fc5f0962d375d
diff --git a/aten/src/ATen/native/cuda/ForeachFunctors.cuh b/aten/src/ATen/native/cuda/ForeachFunctors.cuh
index 7c56368..51fe5c4 100644
--- a/aten/src/ATen/native/cuda/ForeachFunctors.cuh
+++ b/aten/src/ATen/native/cuda/ForeachFunctors.cuh
@@ -1,3 +1,4 @@
+#pragma once
 #include <ATen/native/ForeachUtils.h>
 #include <ATen/native/cuda/MultiTensorApply.cuh>
 
diff --git a/aten/src/ATen/native/cuda/MultiTensorApply.cuh b/aten/src/ATen/native/cuda/MultiTensorApply.cuh
index ab54c11..cb89e14 100644
--- a/aten/src/ATen/native/cuda/MultiTensorApply.cuh
+++ b/aten/src/ATen/native/cuda/MultiTensorApply.cuh
@@ -1,3 +1,4 @@
+#pragma once
 #include <ATen/ATen.h>
 #include <ATen/cuda/CUDAContext.h>
 #include <c10/cuda/CUDAGuard.h>