Fix some Clang-tidy modernize-use-using and Include What You Use warnings; other minor fixes.

Differential revision: https://reviews.llvm.org/D24115

llvm-svn: 280870
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index 23bbace..51a8f287 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -14,13 +14,25 @@
 
 #include "clang/Lex/LiteralSupport.h"
 #include "clang/Basic/CharInfo.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Lex/LexDiagnostic.h"
+#include "clang/Lex/Lexer.h"
 #include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/Token.h"
+#include "llvm/ADT/APInt.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/ErrorHandling.h"
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint> 
+#include <cstring>
+#include <string>
 
 using namespace clang;
 
@@ -135,7 +147,7 @@
       if (Diags)
         Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
              diag::err_hex_escape_no_digits) << "x";
-      HadError = 1;
+      HadError = true;
       break;
     }
 
@@ -453,7 +465,6 @@
   ResultBuf += bytesToWrite;
 }
 
-
 ///       integer-constant: [C99 6.4.4.1]
 ///         decimal-constant integer-suffix
 ///         octal-constant integer-suffix
@@ -986,7 +997,6 @@
   return Result.convertFromString(Str, APFloat::rmNearestTiesToEven);
 }
 
-
 /// \verbatim
 ///       user-defined-character-literal: [C++11 lex.ext]
 ///         character-literal ud-suffix