Remove unused include file (#469)

Author: wenju-he

opencl_clang.cpp

@@ -31,7 +31,6 @@ Copyright (c) Intel Corporation (2009-2017).
 #include "llvm/IR/Metadata.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
 #include "llvm/Bitcode/BitcodeReader.h"
-#include "llvm/Linker/Linker.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/Casting.h"

pch_mgr.cpp

@@ -19,7 +19,6 @@ Copyright (c) Intel Corporation (2009-2017).
 #include "pch_mgr.h"
 
 #include "llvm/ADT/Twine.h"
-#include "llvm/Object/ELF.h"
 
 #include <cstdlib>
 #include <stdio.h>