[clang] [clang-sycl-linker] Make AOT temp files land relative to cwd with unique names (PR #224506)

[Wenju He via cfe-commits]

wenju-he wrote:

OutputFile stem may already have hash, but the change here should be fine since clang-sycl-linker can't assume that OutputFile have hash.

https://github.com/llvm/llvm-project/pull/224506