Fix a typo in walsender.c

[atorikoshi]

Hi,

Attached a minor patch for variable name in comment:  
s/progress_update/update_progress

  ---include/server/replication/logical.h
  ...
  35 typedef struct LogicalDecodingContext
  36 {
  ...
  68 LogicalOutputPluginWriterUpdateProgress update_progress;

Regards,

--
Atsushi Torikoshi
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
diff --git a/src/backend/replication/walsender.c 
b/src/backend/replication/walsender.c
index 130ecd5..d46374d 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1243,7 +1243,7 @@ WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr 
lsn, TransactionId xid,
 }
 
 /*
- * LogicalDecodingContext 'progress_update' callback.
+ * LogicalDecodingContext 'update_progress' callback.
  *
  * Write the current position to the log tracker (see XLogSendPhysical).
  */