[DebugInfo] Move several private headers to include directory

This patch moved the following files in lib/CodeGen/AsmPrinter/
  AsmPrinterHandler.h
  DbgEntityHistoryCalculator.h
  DebugHandlerBase.h
to include/llvm/CodeGen directory.

Such a change will enable Target to extend DebugHandlerBase
and emit Target specific debug info sections.

Signed-off-by: Yonghong Song <yhs@fb.com>

Differential Revision: https://reviews.llvm.org/D55755

llvm-svn: 349564
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 6647346..7070451 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -12,7 +12,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/AsmPrinter.h"
-#include "AsmPrinterHandler.h"
 #include "CodeViewDebug.h"
 #include "DwarfDebug.h"
 #include "DwarfException.h"
@@ -36,6 +35,7 @@
 #include "llvm/BinaryFormat/COFF.h"
 #include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/BinaryFormat/ELF.h"
+#include "llvm/CodeGen/AsmPrinterHandler.h"
 #include "llvm/CodeGen/GCMetadata.h"
 #include "llvm/CodeGen/GCMetadataPrinter.h"
 #include "llvm/CodeGen/GCStrategy.h"