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/Target/PowerPC/PPCTargetStreamer.h b/llvm/lib/Target/PowerPC/PPCTargetStreamer.h
index 6f0125f..74b5f45 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetStreamer.h
+++ b/llvm/lib/Target/PowerPC/PPCTargetStreamer.h
@@ -15,6 +15,7 @@
 namespace llvm {
 class PPCTargetStreamer : public MCTargetStreamer {
 public:
+  PPCTargetStreamer(MCStreamer &S);
   virtual ~PPCTargetStreamer();
   virtual void emitTCEntry(const MCSymbol &S) = 0;
   virtual void emitMachine(StringRef CPU) = 0;