[llvm] [LangRef] asm clobber constrains: '~memory' allows reads and synchronization (PR #150191)

[Ralf Jung via llvm-commits]

RalfJung wrote:

Okay. That sounds out-of-scope for this PR. :)

I don't have merge rights, so once there are enough approvals I'd appreciate if someone cod push this.

https://github.com/llvm/llvm-project/pull/150191