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

llvm-svn: 292983
diff --git a/llvm/lib/Target/SystemZ/Disassembler/SystemZDisassembler.cpp b/llvm/lib/Target/SystemZ/Disassembler/SystemZDisassembler.cpp
index 1806e01..a281a0a 100644
--- a/llvm/lib/Target/SystemZ/Disassembler/SystemZDisassembler.cpp
+++ b/llvm/lib/Target/SystemZ/Disassembler/SystemZDisassembler.cpp
@@ -7,12 +7,16 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "MCTargetDesc/SystemZMCTargetDesc.h"
 #include "SystemZ.h"
 #include "llvm/MC/MCDisassembler/MCDisassembler.h"
 #include "llvm/MC/MCFixedLenDisassembler.h"
 #include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/TargetRegistry.h"
+#include <cassert>
+#include <cstdint>
 
 using namespace llvm;
 
@@ -21,17 +25,19 @@
 typedef MCDisassembler::DecodeStatus DecodeStatus;
 
 namespace {
+
 class SystemZDisassembler : public MCDisassembler {
 public:
   SystemZDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx)
     : MCDisassembler(STI, Ctx) {}
-  ~SystemZDisassembler() override {}
+  ~SystemZDisassembler() override = default;
 
   DecodeStatus getInstruction(MCInst &instr, uint64_t &Size,
                               ArrayRef<uint8_t> Bytes, uint64_t Address,
                               raw_ostream &VStream,
                               raw_ostream &CStream) const override;
 };
+
 } // end anonymous namespace
 
 static MCDisassembler *createSystemZDisassembler(const Target &T,