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/WinCOFFStreamer.cpp b/lib/MC/WinCOFFStreamer.cpp
index 5f3bf3b..8d42d5a 100644
--- a/lib/MC/WinCOFFStreamer.cpp
+++ b/lib/MC/WinCOFFStreamer.cpp
@@ -130,7 +130,7 @@
 
 WinCOFFStreamer::WinCOFFStreamer(MCContext &Context, MCAsmBackend &MAB,
                                  MCCodeEmitter &CE, raw_ostream &OS)
-    : MCObjectStreamer(Context, MAB, OS, &CE), CurSymbol(NULL) {}
+    : MCObjectStreamer(Context, 0, MAB, OS, &CE), CurSymbol(NULL) {}
 
 void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
                                       unsigned ByteAlignment, bool External) {