[SYCL][ROCm] Build lld when ROCm for AMD is enabled

[npmiller]

This patch ensures lld is built by default when the pi_rocm plugin for AMD is enabled as lld is required for linking with that setup.

This should address: #4390

[bader]

I see that we have at least to options to get lld:

1. Find it in the system - [Buildbot][NFC] Add option to use LLD as linker #3866.
2. We have lld sources, so we can build them.

Which of these two we should prefer? Do we need to support them both? If we build lld from sources, can be drop #3866?

[alexbatashev]

I see that we have at least to options to get lld:

1. Find it in the system - [Buildbot][NFC] Add option to use LLD as linker #3866.
2. We have lld sources, so we can build them.

Which of these two we should prefer? Do we need to support them both? If we build lld from sources, can be drop #3866?

I don’t mind always building lld (we may even enable it in CI, I think), but I’m not sure how reliable multistage build is, never tried it before.

[npmiller]

I see that we have at least to options to get lld:

1. Find it in the system - [[Buildbot][NFC] Add option to use LLD as linker #3866](https://github.com/intel/llvm/pull/3866).

2. We have `lld` sources, so we can build them.

Which of these two we should prefer? Do we need to support them both? If we build lld from sources, can be drop #3866?

I think #3866 is still useful even if we always build lld because we may not always want to use lld as the linker for the rest of the build.

I suppose we could skip building lld if --use-lld is passed as it should be available on the system, but lld is also a fairly small part of the build so I think it's fine to have both options.