[clang] [llvm] [clang][SYCL] Add -fno-sycl-rdc to finalize device code per translation unit (PR #218089)

[Tom Honermann via llvm-commits]

================
@@ -95,6 +95,9 @@ def err_drv_hipspv_no_hip_path : Error<
   "'--hip-path' must be specified when offloading to SPIR-V unless '-nogpuinc' "
   "is given">;
 
+def err_drv_sycl_no_rdc_multiple_targets : Error<
+  "'%0' is not supported with multiple SYCL offloading targets">;
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tahonermann wrote:

Is this a fundamental limitation? Or something that could be, and perhaps will be, provided in the future?

If the former, I suggest something like:
```suggestion
def err_drv_sycl_no_rdc_multiple_targets : Error<
  "'%0' cannot be used when multiple SYCL device targets are specified.">;
```

https://github.com/llvm/llvm-project/pull/218089