[MC] Use a unique_ptr<MCAssembler> for MCObjectStreamer's Assembler member.

Removes manual new/delete.

llvm-svn: 315225
diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
index e9e3133..0beaf6b 100644
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -29,15 +29,14 @@
                                    raw_pwrite_stream &OS,
                                    MCCodeEmitter *Emitter_)
     : MCStreamer(Context),
-      Assembler(new MCAssembler(Context, TAB, *Emitter_,
-                                *TAB.createObjectWriter(OS))),
+      Assembler(llvm::make_unique<MCAssembler>(Context, TAB, *Emitter_,
+                                               *TAB.createObjectWriter(OS))),
       EmitEHFrame(true), EmitDebugFrame(false) {}
 
 MCObjectStreamer::~MCObjectStreamer() {
   delete &Assembler->getBackend();
   delete &Assembler->getEmitter();
   delete &Assembler->getWriter();
-  delete Assembler;
 }
 
 void MCObjectStreamer::flushPendingLabels(MCFragment *F, uint64_t FOffset) {