MC: Separate creating a generic object writer from creating a target object writer. NFCI.

With this we gain a little flexibility in how the generic object
writer is created.

Part of PR37466.

Differential Revision: https://reviews.llvm.org/D47045

llvm-svn: 332868
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
index 44ee973..52bf514 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
@@ -417,9 +417,7 @@
   }
 }
 
-std::unique_ptr<MCObjectWriter>
-llvm::createPPCELFObjectWriter(raw_pwrite_stream &OS, bool Is64Bit,
-                               bool IsLittleEndian, uint8_t OSABI) {
-  auto MOTW = llvm::make_unique<PPCELFObjectWriter>(Is64Bit, OSABI);
-  return createELFObjectWriter(std::move(MOTW), OS, IsLittleEndian);
+std::unique_ptr<MCObjectTargetWriter>
+llvm::createPPCELFObjectWriter(bool Is64Bit, uint8_t OSABI) {
+  return llvm::make_unique<PPCELFObjectWriter>(Is64Bit, OSABI);
 }