Add a MCTargetStreamer interface.

This patch fixes an old FIXME by creating a MCTargetStreamer interface
and moving the target specific functions for ARM, Mips and PPC to it.

The ARM streamer is still declared in a common place because it is
used from lib/CodeGen/ARMException.cpp, but the Mips and PPC are
completely hidden in the corresponding Target directories.

I will send an email to llvmdev with instructions on how to use this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192181 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index 8eaa254..78c0094 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -37,7 +37,7 @@
 public:
   MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS,
                   MCCodeEmitter *Emitter)
-      : MCObjectStreamer(Context, MAB, OS, Emitter) {}
+      : MCObjectStreamer(Context, 0, MAB, OS, Emitter) {}
 
   /// @name MCStreamer Interface
   /// @{