[LLDB][REPL] Destroy the repl instances correctly

[wallace]

Summary

This change ensures that the REPL map inside Target is destroyed correctly when Target::Destroy() is invoked. Not doing so results in the REPL not finishing its job when the debugger is initialized in REPL mode reading from a file. In my particular case, my REPL doesn't print the stdout of the last expression in the input file unless I include this change.

lldb/source/Target/Target.cpp

void Target::Destroy() {
   m_last_created_breakpoint.reset();
   m_watchpoint_list.RemoveAll(notify);
   m_last_created_watchpoint.reset();
   m_search_filter_sp.reset();
   m_image_search_paths.Clear(notify);
   m_stop_hooks.clear();
   m_stop_hook_next_id = 0;
   m_suppress_stop_hooks = false;
+  m_repl_map.clear();
   Args signal_args;
   ClearDummySignals(signal_args);
 }
 
 llvm::StringRef Target::GetABIName() const {
   lldb::ABISP abi_sp;
   if (m_process_sp)
     abi_sp = m_process_sp->GetABI();