message: use std streams instead of LLVM's
diff: #include "llvm/Analysis/TargetLibraryInfo.h"
  #include "llvm/Bitcode/BitcodeWriter.h"
  #include "llvm/IR/LegacyPassManager.h"
  -#include "llvm/IR/Module.h"
  #include "llvm/Pass.h"
  #include "llvm/Passes/PassBuilder.h"
  #include "llvm/Passes/PassPlugin.h"
  -#include "llvm/Support/raw_ostream.h"
  #include <fstream>
  #include <iostream>
  #include <memory>
  @@ -122,13 +120,12 @@ void writeBitcode(const fs::path &report_filename) {
  bc_filename.replace_extension(".bc");
  }
  - std::error_code EC;
  - llvm::raw_fd_ostream bc_file(bc_filename.string(), EC);
  - if (EC) {
  + ofstream bc_file(bc_filename);
  + if (!bc_file.is_open()) {
  cerr << "Alive2: Couldn't open bitcode file" << endl;
  exit(1);
  }
  - bc_file.write(SavedBitcode.data(), SavedBitcode.size());
  + bc_file << SavedBitcode;
  bc_file.close();
  *out << "Wrote bitcode to: " << bc_filename << '\n';
  }
  