health_check_using_rpc: remove unnecessary friend class

src/brpc/channel.h

@@ -146,7 +146,6 @@ private:
 class Channel : public ChannelBase {
 friend class Controller;
 friend class SelectiveChannel;
-friend class HealthCheckTask;
 public:
     Channel(ProfilerLinker = ProfilerLinker());
     ~Channel();

src/brpc/socket.cpp

@@ -1084,7 +1084,7 @@ bool HealthCheckTask::OnTriggeringTask(timespec* next_abstime) {
                     << cntl.ErrorText();
                 // the hc rpc above may fail too, we should handle this case
                 // carefully. If this rpc fails, hc must be triggered again.
-                // One Solution is to trigger the second hc in Socket::SetFailed
+                // One solution is to trigger the second hc in Socket::SetFailed
                 // in rpc code path, but rpc fails doesn't mean socket fails,
                 // so we should call Socket::SetFailed[1] explicitly here.
                 // But there is a race here: