[Support] Fix lifetime of file descriptors when using MemoryBuffer.

Clients of MemoryBuffer::getOpenFile expect it not to take ownership of the file
descriptor passed in. So don't.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176995 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/FileOutputBuffer.cpp b/lib/Support/FileOutputBuffer.cpp
index cd430f2..1ee69b6 100644
--- a/lib/Support/FileOutputBuffer.cpp
+++ b/lib/Support/FileOutputBuffer.cpp
@@ -70,8 +70,8 @@
   if (EC)
     return EC;
 
-  OwningPtr<mapped_file_region> MappedFile(
-    new mapped_file_region(FD, mapped_file_region::readwrite, Size, 0, EC));
+  OwningPtr<mapped_file_region> MappedFile(new mapped_file_region(
+      FD, true, mapped_file_region::readwrite, Size, 0, EC));
   if (EC)
     return EC;