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

llvm-svn: 309230
diff --git a/llvm/lib/Target/Hexagon/HexagonBlockRanges.cpp b/llvm/lib/Target/Hexagon/HexagonBlockRanges.cpp
index 1640b40..34a886f 100644
--- a/llvm/lib/Target/Hexagon/HexagonBlockRanges.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonBlockRanges.cpp
@@ -1,4 +1,4 @@
-//===--- HexagonBlockRanges.cpp -------------------------------------------===//
+//===- HexagonBlockRanges.cpp ---------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -24,8 +24,10 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include <algorithm>
 #include <cassert>
+#include <cstdint>
 #include <iterator>
 #include <map>
+#include <utility>
 
 using namespace llvm;