[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/WinCFGuard.h b/llvm/lib/CodeGen/AsmPrinter/WinCFGuard.h
index 124e8f0..28f119e 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinCFGuard.h
+++ b/llvm/lib/CodeGen/AsmPrinter/WinCFGuard.h
@@ -14,7 +14,7 @@
 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_WINCFGUARD_H
 #define LLVM_LIB_CODEGEN_ASMPRINTER_WINCFGUARD_H
 
-#include "AsmPrinterHandler.h"
+#include "llvm/CodeGen/AsmPrinterHandler.h"
 #include "llvm/Support/Compiler.h"
 
 namespace llvm {