[CodeView] Fix some Clang-tidy modernize-use-using and Include What You Use warnings; other minor fixes (NFC).

llvm-svn: 306616
diff --git a/llvm/lib/DebugInfo/CodeView/DebugLinesSubsection.cpp b/llvm/lib/DebugInfo/CodeView/DebugLinesSubsection.cpp
index fbcad61..57ad408 100644
--- a/llvm/lib/DebugInfo/CodeView/DebugLinesSubsection.cpp
+++ b/llvm/lib/DebugInfo/CodeView/DebugLinesSubsection.cpp
@@ -1,4 +1,4 @@
-//===- DebugLinesSubsection.cpp -------------------------------*- C++-*-===//
+//===- DebugLinesSubsection.cpp -------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -8,18 +8,21 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/CodeView/DebugLinesSubsection.h"
-
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/DebugInfo/CodeView/CodeView.h"
 #include "llvm/DebugInfo/CodeView/CodeViewError.h"
 #include "llvm/DebugInfo/CodeView/DebugChecksumsSubsection.h"
-#include "llvm/DebugInfo/CodeView/DebugStringTableSubsection.h"
-#include "llvm/DebugInfo/CodeView/DebugSubsectionRecord.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/BinaryStreamWriter.h"
+#include "llvm/Support/Error.h"
+#include <cassert>
+#include <cstdint>
 
 using namespace llvm;
 using namespace llvm::codeview;
 
 Error LineColumnExtractor::operator()(BinaryStreamRef Stream, uint32_t &Len,
                                       LineColumnEntry &Item) {
-  using namespace codeview;
   const LineBlockFragmentHeader *BlockHeader;
   BinaryStreamReader Reader(Stream);
   if (auto EC = Reader.readObject(BlockHeader))