[llvm] Fixed build with C++20 standard (PR #169772)

[Jonathan Wakely via llvm-commits]

https://github.com/jwakely commented:

As noted at https://github.com/llvm/llvm-project/issues/139072#issuecomment-2888894075 there are other operators which should really be constrained similarly. So this fixes the immediate issue, but there are still latent bugs that might cause similar errors later.

https://github.com/llvm/llvm-project/pull/169772