LangRef: Clarify expected sNaN behavior for minnum/maxnum

This matches the de-facto behavior based on constant folding
and the default lowering to fmin/fmax.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340762 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed