MemoryBuffer API update.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@121956 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index bbabf80..a4ba496 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2278,7 +2278,7 @@
   std::string ErrStr;
   llvm::error_code ec;
   if (FileName == "-") {
-    F.Buffer.reset(llvm::MemoryBuffer::getSTDIN(ec));
+    ec = llvm::MemoryBuffer::getSTDIN(F.Buffer);
     if (ec)
       ErrStr = ec.message();
   } else