message: [GDBRemote] Reflow comments and improve docs.
  Improved the GDB client base documentation while I was reading through
  it. Looks like it got messed up during the automatic comment reflow a
  while ago.
diff: @@ -24,12 +24,10 @@ public:
  virtual void HandleAsyncMisc(llvm::StringRef data) = 0;
  virtual void HandleStopReply() = 0;
  - // =========================================================================
  /// Process asynchronously-received structured data.
  ///
  /// \param[in] data
  /// The complete data packet, expected to start with JSON-async.
  - // =========================================================================
  virtual void HandleAsyncStructuredDataPacket(llvm::StringRef data) = 0;
  };
  @@ -83,42 +81,48 @@ protected:
  virtual void OnRunPacketSent(bool first);
  private:
  - // Variables handling synchronization between the Continue thread and any
  - // other threads
  - // wishing to send packets over the connection. Either the continue thread has
  - // control over
  - // the connection (m_is_running == true) or the connection is free for an
  - // arbitrary number of
  - // other senders to take which indicate their interest by incrementing
  - // m_async_count.
  - // Semantics of individual states:
  - // - m_continue_packet == false, m_async_count == 0: connection is free
  - // - m_continue_packet == true, m_async_count == 0: only continue thread is
  - // present
  - // - m_continue_packet == true, m_async_count > 0: continue thread has
  - // control, async threads
  - // should interrupt it and wait for it to set m_continue_packet to false
  - // - m_continue_packet == false, m_async_count > 0: async threads have
  - // control, continue
  - // thread needs to wait for them to finish (m_async_count goes down to 0).
  + /// Variables handling synchronization between the Continue thread and any
  + /// other threads wishing to send packets over the connection. Either the
  + /// continue thread has control over the connection (m_is_running == true) or
  + /// the connection is free for an arbitrary number of other senders to take
  + /// which indicate their interest by incrementing m_async_count.
  + ///
  + /// Semantics of individual states:
  + ///
  + /// - m_continue_packet == false, m_async_count == 0:
  + /// connection is free
  + /// - m_continue_packet == true, m_async_count == 0:
  + /// only continue thread is present
  + /// - m_continue_packet == true, m_async_count > 0:
  + /// continue thread has control, async threads should interrupt it and wait
  + /// for it to set m_continue_packet to false
  + /// - m_continue_packet == false, m_async_count > 0:
  + /// async threads have control, continue thread needs to wait for them to
  + /// finish (m_async_count goes down to 0).
  + /// @{
  std::mutex m_mutex;
  std::condition_variable m_cv;
  - // Packet with which to resume after an async interrupt. Can be changed by an
  - // async thread
  - // e.g. to inject a signal.
  +
  + /// Packet with which to resume after an async interrupt. Can be changed by
  + /// an async thread e.g. to inject a signal.
  std::string m_continue_packet;
  - // When was the interrupt packet sent. Used to make sure we time out if the
  - // stub does not
  - // respond to interrupt requests.
  +
  + /// When was the interrupt packet sent. Used to make sure we time out if the
  + /// stub does not respond to interrupt requests.
  std::chrono::time_point<std::chrono::steady_clock> m_interrupt_time;
  +
  + /// Number of threads interested in sending.
  uint32_t m_async_count;
  +
  + /// Whether the continue thread has control.
  bool m_is_running;
  - bool m_should_stop; // Whether we should resume after a stop.
  - // end of continue thread synchronization block
  - // This handles the synchronization between individual async threads. For now
  - // they just use a
  - // simple mutex.
  + /// Whether we should resume after a stop.
  + bool m_should_stop;
  + /// @}
  +
  + /// This handles the synchronization between individual async threads. For
  + /// now they just use a simple mutex.
  std::recursive_mutex m_async_mutex;
  bool ShouldStop(const UnixSignals &signals,
  