[amd] fix unused variable device_flags (#120369)
Summary:
get build error due to D53986297 (https://github.com/pytorch/pytorch/pull/119996)
```
caffe2/c10/cuda/__fb_c10_hipify_gen__/out/c10/hip/HIPStream.cpp:40:23: error: unused variable 'device_flags' [-Werror,-Wunused-variable]
static c10::once_flag device_flags[C10_COMPILE_TIME_MAX_GPUS];
```
Reviewed By: jianyuh, xw285cornell
Differential Revision: D54027737
Pull Request resolved: https://github.com/pytorch/pytorch/pull/120369
Approved by: https://github.com/xw285cornell, https://github.com/jianyuh
diff --git a/c10/cuda/CUDAStream.cpp b/c10/cuda/CUDAStream.cpp
index 54beb63..0569e35 100644
--- a/c10/cuda/CUDAStream.cpp
+++ b/c10/cuda/CUDAStream.cpp
@@ -36,7 +36,10 @@
// already been destroyed and thus invoking cudaStreamDestroy could lead to a
// crash. It's likely an issue in CUDA, but to be safe - let's just "forget"
// the destruction.
+#if !defined(USE_ROCM)
+// CUDA-only: used to initializes the stream pools (once)
static c10::once_flag device_flags[C10_COMPILE_TIME_MAX_GPUS];
+#endif
static std::atomic<uint32_t>
priority_counters[c10::cuda::max_compile_time_stream_priorities]
[C10_COMPILE_TIME_MAX_GPUS];
