[clang] [llvm] [Driver][SYCL] Add initial SYCL offload compilation support (PR #117268)

[Jon Roelofs via llvm-commits]

jroelofs wrote:

I see a new warning from this patch:
```
clang/lib/Driver/ToolChains/SYCL.cpp:35:10: warning: returning address of local temporary object [-Wreturn-stack-address]
```

https://github.com/llvm/llvm-project/pull/117268