Replace OwningPtr<T> with std::unique_ptr<T>.

This compiles with no changes to clang/lld/lldb with MSVC and includes
overloads to various functions which are used by those projects and llvm
which have OwningPtr's as parameters. This should allow out of tree
projects some time to move. There are also no changes to libs/Target,
which should help out of tree targets have time to move, if necessary.

llvm-svn: 203083
diff --git a/llvm/utils/FileCheck/FileCheck.cpp b/llvm/utils/FileCheck/FileCheck.cpp
index b0196f7..a1f4be9 100644
--- a/llvm/utils/FileCheck/FileCheck.cpp
+++ b/llvm/utils/FileCheck/FileCheck.cpp
@@ -16,7 +16,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringMap.h"
@@ -821,7 +820,7 @@
 /// Returns true in case of an error, false otherwise.
 static bool ReadCheckFile(SourceMgr &SM,
                           std::vector<CheckString> &CheckStrings) {
-  OwningPtr<MemoryBuffer> File;
+  std::unique_ptr<MemoryBuffer> File;
   if (error_code ec =
         MemoryBuffer::getFileOrSTDIN(CheckFilename, File)) {
     errs() << "Could not open check file '" << CheckFilename << "': "
@@ -1218,7 +1217,7 @@
     return 2;
 
   // Open the file to check and add it to SourceMgr.
-  OwningPtr<MemoryBuffer> File;
+  std::unique_ptr<MemoryBuffer> File;
   if (error_code ec =
         MemoryBuffer::getFileOrSTDIN(InputFilename, File)) {
     errs() << "Could not open input file '" << InputFilename << "': "