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/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
index 9a01792..4fb12d4 100644
--- a/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
+++ b/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp
@@ -121,9 +121,7 @@
   }
 }
 
-std::unique_ptr<MCObjectWriter>
-llvm::createWebAssemblyWasmObjectWriter(raw_pwrite_stream &OS,
-                                        bool Is64Bit) {
-  auto MOTW = llvm::make_unique<WebAssemblyWasmObjectWriter>(Is64Bit);
-  return createWasmObjectWriter(std::move(MOTW), OS);
+std::unique_ptr<MCObjectTargetWriter>
+llvm::createWebAssemblyWasmObjectWriter(bool Is64Bit) {
+  return llvm::make_unique<WebAssemblyWasmObjectWriter>(Is64Bit);
 }