Move legacy LTO interface headers to legacy/ directory.

Differential Revision: https://reviews.llvm.org/D22173

llvm-svn: 275476
diff --git a/llvm/tools/lto/lto.cpp b/llvm/tools/lto/lto.cpp
index 0c36c99..7109cf4 100644
--- a/llvm/tools/lto/lto.cpp
+++ b/llvm/tools/lto/lto.cpp
@@ -19,9 +19,9 @@
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/LLVMContext.h"
-#include "llvm/LTO/LTOCodeGenerator.h"
-#include "llvm/LTO/LTOModule.h"
-#include "llvm/LTO/ThinLTOCodeGenerator.h"
+#include "llvm/LTO/legacy/LTOCodeGenerator.h"
+#include "llvm/LTO/legacy/LTOModule.h"
+#include "llvm/LTO/legacy/ThinLTOCodeGenerator.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/TargetSelect.h"