[SDPatternMatcher] Remove std::optional around SDNodeFlags in BinaryOpc_match. NFC (#160178)

Using all 0 flags as the default works correctly. We'll get (0 &
N->getFlags()) == 0 which is always true which is what we want.

Author: topperc

llvm/include/llvm/CodeGen/SDPatternMatch.h

@@ -597,9 +597,9 @@ struct BinaryOpc_match {
   unsigned Opcode;
   LHS_P LHS;
   RHS_P RHS;
-  std::optional<SDNodeFlags> Flags;
+  SDNodeFlags Flags;
   BinaryOpc_match(unsigned Opc, const LHS_P &L, const RHS_P &R,
-                  std::optional<SDNodeFlags> Flgs = std::nullopt)
+                  SDNodeFlags Flgs = SDNodeFlags())
       : Opcode(Opc), LHS(L), RHS(R), Flags(Flgs) {}
 
   template <typename MatchContext>
@@ -613,10 +613,7 @@ struct BinaryOpc_match {
              RHS.match(Ctx, N->getOperand(EO.FirstIndex)))))
         return false;
 
-      if (!Flags.has_value())
-        return true;
-
-      return (*Flags & N->getFlags()) == *Flags;
+      return (Flags & N->getFlags()) == Flags;
     }
 
     return false;