[SelectionDAG] Add the fpexcept flag to the SelectionDAG dumping output so we can better see when its not propagating.

We're currently losing this flag in type legalization and probably
other places when we expand strict fp nodes. This will make
reading logs easier.

llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp

@@ -543,6 +543,9 @@ void SDNode::print_details(raw_ostream &OS, const SelectionDAG *G) const {
   if (getFlags().hasVectorReduction())
     OS << " vector-reduction";
 
+  if (getFlags().hasFPExcept())
+    OS << " fpexcept";
+
   if (const MachineSDNode *MN = dyn_cast<MachineSDNode>(this)) {
     if (!MN->memoperands_empty()) {
       OS << "<";