Deduplicate #include (#458)

Author: MichalStrehovsky

llvm/tools/objwriter/debugInfo/dwarf/dwarfGen.cpp

@@ -12,7 +12,6 @@
 
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/MC/MCContext.h"
-#include "llvm/BinaryFormat/ELF.h"
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCAsmInfo.h"