Update the MemoryBuffer API to use ErrorOr.

llvm-svn: 212405
diff --git a/llvm/tools/llvm-mc/llvm-mc.cpp b/llvm/tools/llvm-mc/llvm-mc.cpp
index 72294ca..4c5b230 100644
--- a/llvm/tools/llvm-mc/llvm-mc.cpp
+++ b/llvm/tools/llvm-mc/llvm-mc.cpp
@@ -367,13 +367,13 @@
   if (!TheTarget)
     return 1;
 
-  std::unique_ptr<MemoryBuffer> BufferPtr;
-  if (std::error_code ec =
-          MemoryBuffer::getFileOrSTDIN(InputFilename, BufferPtr)) {
-    errs() << ProgName << ": " << ec.message() << '\n';
+  ErrorOr<std::unique_ptr<MemoryBuffer>> BufferPtr =
+      MemoryBuffer::getFileOrSTDIN(InputFilename);
+  if (std::error_code EC = BufferPtr.getError()) {
+    errs() << ProgName << ": " << EC.message() << '\n';
     return 1;
   }
-  MemoryBuffer *Buffer = BufferPtr.release();
+  MemoryBuffer *Buffer = BufferPtr->release();
 
   SourceMgr SrcMgr;