[clang] [libclc] libclc: remove __attribute__((assume)) for clspv targets (PR #92126)

[Erich Keane via cfe-commits]

erichkeane wrote:

> @erichkeane, I don't know what you expect for the release note, where should I write something?

See `ReleaseNotes.rst`, find a section that makes sense (probably attribute changes), and write a quick blurb about the attribute, likely a very condensed version of the docs.

https://github.com/llvm/llvm-project/pull/92126