Construct the MCStreamer before constructing the MCTargetStreamer.

This has a few advantages:
* Only targets that use a MCTargetStreamer have to worry about it.
* There is never a MCTargetStreamer without a MCStreamer, so we can use a
  reference.
* A MCTargetStreamer can talk to the MCStreamer in its constructor.

llvm-svn: 200129
diff --git a/llvm/lib/MC/MCELFStreamer.cpp b/llvm/lib/MC/MCELFStreamer.cpp
index 8c9ad63..1f87f3d 100644
--- a/llvm/lib/MC/MCELFStreamer.cpp
+++ b/llvm/lib/MC/MCELFStreamer.cpp
@@ -543,12 +543,10 @@
   this->MCObjectStreamer::FinishImpl();
 }
 
-MCStreamer *llvm::createELFStreamer(MCContext &Context,
-                                    MCTargetStreamer *Streamer,
-                                    MCAsmBackend &MAB, raw_ostream &OS,
-                                    MCCodeEmitter *CE, bool RelaxAll,
-                                    bool NoExecStack) {
-  MCELFStreamer *S = new MCELFStreamer(Context, Streamer, MAB, OS, CE);
+MCStreamer *llvm::createELFStreamer(MCContext &Context, MCAsmBackend &MAB,
+                                    raw_ostream &OS, MCCodeEmitter *CE,
+                                    bool RelaxAll, bool NoExecStack) {
+  MCELFStreamer *S = new MCELFStreamer(Context, MAB, OS, CE);
   if (RelaxAll)
     S->getAssembler().setRelaxAll(true);
   if (NoExecStack)