Split the object streamer callback in one per file format.

There are two main advantages to doing this

* Targets that only need to handle one of the formats specially don't have
  to worry about the others. For example, x86 now only registers a
  constructor for the COFF streamer.

* Changes to the arguments passed to one format constructor will not impact
  the other formats.

llvm-svn: 232699
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp
index b344ced..dc707dc 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp
@@ -37,10 +37,10 @@
 }
 }
 
-namespace llvm {
-MCStreamer *createARMWinCOFFStreamer(MCContext &Context, MCAsmBackend &MAB,
-                                     MCCodeEmitter &Emitter, raw_ostream &OS) {
-  return new ARMWinCOFFStreamer(Context, MAB, Emitter, OS);
-}
+MCStreamer *llvm::createARMWinCOFFStreamer(MCContext &Context,
+                                           MCAsmBackend &MAB, raw_ostream &OS,
+                                           MCCodeEmitter *Emitter,
+                                           bool RelaxAll) {
+  return new ARMWinCOFFStreamer(Context, MAB, *Emitter, OS);
 }