[NFC][Debugify][Original DI] Use MapVector insted of DenseMap for DI tracking

[djtodoro]

Summary

By using MapVector instead of DenseMap, reporting issues will be in deterministic order.

[jmorse]

LGTM

[djtodoro]

@jmorse Thanks!

llvm/include/llvm/Transforms/Utils/Debugify.h

 //===- Debugify.h - Check debug info preservation in optimizations --------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file Interface to the `debugify` synthetic/original debug info testing
 /// utility.
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_TRANSFORMS_UTILS_DEBUGIFY_H
 #define LLVM_TRANSFORMS_UTILS_DEBUGIFY_H
 
-#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Bitcode/BitcodeWriterPass.h"
 #include "llvm/IR/IRPrintingPasses.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/ValueHandle.h"
 
-using DebugFnMap = llvm::DenseMap<llvm::StringRef, const llvm::DISubprogram *>;
-using DebugInstMap = llvm::DenseMap<const llvm::Instruction *, bool>;
-using DebugVarMap = llvm::DenseMap<const llvm::DILocalVariable *, unsigned>;
+using DebugFnMap = llvm::MapVector<llvm::StringRef, const llvm::DISubprogram *>;
+using DebugInstMap = llvm::MapVector<const llvm::Instruction *, bool>;
+using DebugVarMap = llvm::MapVector<const llvm::DILocalVariable *, unsigned>;
 using WeakInstValueMap =
-    llvm::DenseMap<const llvm::Instruction *, llvm::WeakVH>;
+    llvm::MapVector<const llvm::Instruction *, llvm::WeakVH>;
 
 /// Used to track the Debug Info Metadata information.
 struct DebugInfoPerPass {
   // This maps a function name to its associated DISubprogram.
   DebugFnMap DIFunctions;
   // This maps an instruction and the info about whether it has !dbg attached.
   DebugInstMap DILocations;
   // This tracks value (instruction) deletion. If an instruction gets deleted,