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

llvm-svn: 306169
diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
index f0caf2e..475cf25 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
@@ -8,7 +8,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/DebugInfo/DWARF/DWARFDebugFrame.h"
-
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/Optional.h"
@@ -71,7 +70,7 @@
 
   /// An entry may contain CFI instructions. An instruction consists of an
   /// opcode and an optional sequence of operands.
-  typedef std::vector<uint64_t> Operands;
+  using Operands = std::vector<uint64_t>;
   struct Instruction {
     Instruction(uint8_t Opcode)
       : Opcode(Opcode)