[llvm] [SYCL] Add platform enumeration and info query using liboffload (PR #166927)

[Andrei Elovikov via llvm-commits]

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@@ -49,7 +47,7 @@ function(add_sycl_rt_library LIB_TARGET_NAME LIB_OBJ_NAME LIB_OUTPUT_NAME)
     target_compile_options(${LIB_OBJ_NAME} PUBLIC /EHsc)
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aelovikov-intel wrote:

I think we need 

https://github.com/llvm/llvm-project/blob/9cca883dd031ba495f9d45d21e30b05af69c2c75/clang/docs/UsersManual.rst?plain=1#L5047

here. We couldn't do that downstream because we support building with MSVC there (and aren't using `LLVM_ENABLE_RUNTIMES`) that doesn't have support for that option, but in this upstream version we know that we're building with a freshly built clang and the option is available to us.

https://github.com/llvm/llvm-project/pull/166927