Reland libclc patches reverted in sycl-web

[maarquitos14]

Describe the bug

A lot of libclc-related patches are coming in from upstream causing massive conflicts in sycl-web. Some of them are not easy to apply without deep knowledge of libclc, so they were just reverted and need to be relanded. Please, see below a list of the reverted patches:

• llvm/llvm-project@7be30fd
• llvm/llvm-project@b231647

Please, feel free to edit the description to add new reverted patches.

[frasercrmck]

I think we could perhaps close this issue and re-open another one when a new batch of commits comes in. Otherwise this ticket will be open forever 😄