[llvm] [LangRef] Clarify specification for float min/max operations (PR #172012)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> We can do either. Is there one option that's better for backends / follow-up optimizations? 

Folding to the qNaN will allow more downstream operations to fold, since just about everything else simply propagates input nans 


https://github.com/llvm/llvm-project/pull/172012