MCObjectWriter.h - remove unnecessary includes. NFC

The EndianStream.h/raw_ostream.h headers should be removed as well but we have a lot of other files that are implicitly relying on them being present.

Author: RKSimon

llvm/include/llvm/MC/MCObjectWriter.h

@@ -9,13 +9,10 @@
 #ifndef LLVM_MC_MCOBJECTWRITER_H
 #define LLVM_MC_MCOBJECTWRITER_H
 
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/EndianStream.h"
 #include "llvm/Support/raw_ostream.h"
-#include <cassert>
 #include <cstdint>
 
 namespace llvm {