message: don't spew LLVM IR output unless loglevel>=2
diff: @@ -158,7 +158,9 @@ std::unique_ptr<Executable> Compiler::CompileProgram(const stripe::Block& progra
  llvm::legacy::PassManager modopt;
  pmb.populateModulePassManager(modopt);
  modopt.run(*module_);
  + if (VLOG_IS_ON(2)) {
  module_->print(llvm::errs(), nullptr);
  + }
  // Wrap the finished module and the buffer names into an Executable instance.
  std::vector<std::string> param_names;
  for (auto& ref : program.refs) {
  