[llvm] [SDAG] Read-only intrinsics must have WillReturn attribute to be treated as loads (PR #99999)

[Kevin McAfee via llvm-commits]

kalxr wrote:

I found many intrinsics for which `OnlyLoad` would have been `true` that would now be `false` with the `willReturn()` check. Most of these look like loads that should have `IntrWillReturn`, so I'll open another PR to fix them.

https://github.com/llvm/llvm-project/pull/99999