message: Call a callback to emit the merged object file.
diff: use crate::config::LLVM;
  use crate::trampoline::FuncTrampoline;
  use crate::translator::FuncTranslator;
  +use crate::CompiledFunctionKind;
  use inkwell::context::Context;
  use inkwell::memory_buffer::MemoryBuffer;
  use inkwell::module::Module;
  @@ -194,6 +195,12 @@ impl LLVMCompiler {
  let memory_buffer = target_machine
  .write_to_memory_buffer(&merged_module, FileType::Object)
  .unwrap();
  + if let Some(ref callbacks) = self.config.callbacks {
  + callbacks.obj_memory_buffer(
  + &CompiledFunctionKind::Local(function_body_inputs.iter().next().unwrap().0),
  + &memory_buffer,
  + );
  + }
  Ok(memory_buffer.as_slice().to_vec())
  }
  