[lldb] [llgs] Remove not-really-used m_inferior_prev_state

[mgorny]

Summary

Remove m_inferior_prev_state that's not suitable for multiprocess
debugging and that does not seem to be really used at all.

The only use of the variable right now is to "prevent" sending the stop
reason after attach/launch. However, this code is never actually run
since none of the process plugins actually use eStateLaunching or
eStateAttaching. Through adding an assert, I've confirmed that it's
never hit in any of the LLDB tests or while attaching/launching debugged
process via lldb-server and via lldb CLI.

Sponsored by: The FreeBSD Foundation

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h

protected:
   NativeProcessProtocol *m_current_process;
   NativeProcessProtocol *m_continue_process;
   std::recursive_mutex m_debugged_process_mutex;
   std::unordered_map<lldb::pid_t, DebuggedProcess> m_debugged_processes;
 
   Communication m_stdio_communication;
   MainLoop::ReadHandleUP m_stdio_handle_up;
 
-  lldb::StateType m_inferior_prev_state = lldb::StateType::eStateInvalid;
   llvm::StringMap<std::unique_ptr<llvm::MemoryBuffer>> m_xfer_buffer_map;
   std::mutex m_saved_registers_mutex;
   std::unordered_map<uint32_t, lldb::DataBufferSP> m_saved_registers_map;
   uint32_t m_next_saved_registers_id = 1;
   bool m_thread_suffix_supported = false;
   bool m_list_threads_in_stop_reply = false;
   bool m_non_stop = false;
   std::deque<std::string> m_stop_notification_queue;

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp

 
 void GDBRemoteCommunicationServerLLGS::HandleInferiorState_Stopped(
     NativeProcessProtocol *process) {
   assert(process && "process cannot be NULL");
 
   Log *log = GetLog(LLDBLog::Process);
   LLDB_LOGF(log, "GDBRemoteCommunicationServerLLGS::%s called", __FUNCTION__);
 
-  // Send the stop reason unless this is the stop after the launch or attach.
-  switch (m_inferior_prev_state) {
-  case eStateLaunching:
-  case eStateAttaching:
-    // Don't send anything per debugserver behavior.
-    break;
-  default:
-    // In all other cases, send the stop reason.
-    PacketResult result = SendStopReasonForState(
-        *process, StateType::eStateStopped, /*force_synchronous=*/false);
-    if (result != PacketResult::Success) {
-      LLDB_LOGF(log,
-                "GDBRemoteCommunicationServerLLGS::%s failed to send stop "
-                "notification for PID %" PRIu64 ", state: eStateExited",
-                __FUNCTION__, process->GetID());
-    }
-    break;
-  }
 }
 
 void GDBRemoteCommunicationServerLLGS::ProcessStateChanged(
     NativeProcessProtocol *process, lldb::StateType state) {
   assert(process && "process cannot be NULL");
   Log *log = GetLog(LLDBLog::Process);
   if (log) {
     LLDB_LOGF(log,
default:
     if (log) {
       LLDB_LOGF(log,
                 "GDBRemoteCommunicationServerLLGS::%s didn't handle state "
                 "change for pid %" PRIu64 ", new state: %s",
                 __FUNCTION__, process->GetID(), StateAsCString(state));
     }
     break;
   }
-
-  // Remember the previous state reported to us.
-  m_inferior_prev_state = state;
 }
 
 void GDBRemoteCommunicationServerLLGS::DidExec(NativeProcessProtocol *process) {
   ClearProcessSpecificData();
 }
 
 void GDBRemoteCommunicationServerLLGS::NewSubprocess(
     NativeProcessProtocol *parent_process,