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/X86/MCTargetDesc/X86MCTargetDesc.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
index afcc953..2e1644d 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp
@@ -344,22 +344,6 @@
   return X;
 }
 
-static MCStreamer *createMCStreamer(const Triple &T, MCContext &Ctx,
-                                    MCAsmBackend &MAB, raw_ostream &OS,
-                                    MCCodeEmitter *Emitter,
-                                    const MCSubtargetInfo &STI, bool RelaxAll) {
-  switch (T.getObjectFormat()) {
-  default: llvm_unreachable("unsupported object format");
-  case Triple::MachO:
-    return createMachOStreamer(Ctx, MAB, OS, Emitter, RelaxAll);
-  case Triple::COFF:
-    assert(T.isOSWindows() && "only Windows COFF is supported");
-    return createX86WinCOFFStreamer(Ctx, MAB, Emitter, OS, RelaxAll);
-  case Triple::ELF:
-    return createELFStreamer(Ctx, MAB, OS, Emitter, RelaxAll);
-  }
-}
-
 static MCInstPrinter *createX86MCInstPrinter(const Target &T,
                                              unsigned SyntaxVariant,
                                              const MCAsmInfo &MAI,
@@ -414,7 +398,7 @@
     TargetRegistry::RegisterMCCodeEmitter(*T, createX86MCCodeEmitter);
 
     // Register the object streamer.
-    TargetRegistry::RegisterMCObjectStreamer(*T, createMCStreamer);
+    TargetRegistry::RegisterCOFFStreamer(*T, createX86WinCOFFStreamer);
 
     // Register the MCInstPrinter.
     TargetRegistry::RegisterMCInstPrinter(*T, createX86MCInstPrinter);