This PR adds support for AOT compilation for Intel CPUs and GPUs in
clang-sycl-linker. When no `-arch` is passed to `clang-sycl-linker`, the
output of the tool will be the resulting linked SPIR-V bytecode. If the
`-arch` is passed to `clang-sycl-linker` and the value is a supported
Intel CPU or GPU, then SPIR-V bytecode is then further passed to the
respective tool (`opencl-aot` or `ocloc`) for AOT compilation.
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