unique_ptrify IRObjectFile::createIRObjectFile

I took a guess at the changes to the gold plugin, because that doesn't
seem to build by default for me. Not sure what dependencies I might be
missing for that.

llvm-svn: 217056
diff --git a/llvm/lib/Object/SymbolicFile.cpp b/llvm/lib/Object/SymbolicFile.cpp
index 17624a3..f8dd4b3 100644
--- a/llvm/lib/Object/SymbolicFile.cpp
+++ b/llvm/lib/Object/SymbolicFile.cpp
@@ -33,8 +33,7 @@
   switch (Type) {
   case sys::fs::file_magic::bitcode:
     if (Context)
-      return ErrorOr<std::unique_ptr<SymbolicFile>>(
-          IRObjectFile::createIRObjectFile(Object, *Context));
+      return IRObjectFile::createIRObjectFile(Object, *Context);
   // Fallthrough
   case sys::fs::file_magic::unknown:
   case sys::fs::file_magic::archive: