[CIR][NFC] Fix init llvm::ArrayRef warning (#146147)

Fix init llvm::ArrayRef deprecation warning when initialized with
std::nullopt

Author: AmrDeveloper

clang/lib/CIR/CodeGen/CIRGenCall.cpp

@@ -404,7 +404,7 @@ CIRGenTypes::arrangeFunctionDeclaration(const FunctionDecl *fd) {
           funcTy.getAs<FunctionNoProtoType>()) {
     assert(!cir::MissingFeatures::opCallCIRGenFuncInfoExtParamInfo());
     assert(!cir::MissingFeatures::opCallFnInfoOpts());
-    return arrangeCIRFunctionInfo(noProto->getReturnType(), std::nullopt,
+    return arrangeCIRFunctionInfo(noProto->getReturnType(), {},
                                   RequiredArgs::All);
   }
 

clang/lib/CIR/CodeGen/CIRGenFunction.h

@@ -894,9 +894,8 @@ class CIRGenFunction : public CIRGenTypeCache {
 
   // Build CIR for a statement. useCurrentScope should be true if no
   // new scopes need be created when finding a compound statement.
-  mlir::LogicalResult
-  emitStmt(const clang::Stmt *s, bool useCurrentScope,
-           llvm::ArrayRef<const Attr *> attrs = std::nullopt);
+  mlir::LogicalResult emitStmt(const clang::Stmt *s, bool useCurrentScope,
+                               llvm::ArrayRef<const Attr *> attrs = {});
 
   mlir::LogicalResult emitSimpleStmt(const clang::Stmt *s,
                                      bool useCurrentScope);