[llvm] [Remarks] Emit SROA and mem2reg missed remarks (PR #221094)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

If we can come up with a better way to show the user useful information about optimizations, that sounds like a good idea.  Not sure exactly what that looks like.

Not sure what you're suggesting with respect to this patch, though.

https://github.com/llvm/llvm-project/pull/221094