Remove unused function that did nothing.

src/backend/access/transam/twophase.c

@@ -1922,15 +1922,6 @@ RecordTransactionAbortPrepared(TransactionId xid,
 	SyncRepWaitForLSN(recptr);
 }
 
-int
-TwoPhaseRecoverMirror(void)
-{
-	int			retval = 0;
-
-	/* No need to do anything. */
-	return retval;
-}
-
 /*
  * This function will gather up all the current prepared transaction xlog pointers,
  * and pass that information back to the caller.

src/include/access/twophase.h

@@ -85,8 +85,6 @@ extern void CheckPointTwoPhase(XLogRecPtr redo_horizon);
 
 extern bool FinishPreparedTransaction(const char *gid, bool isCommit, bool raiseErrorIfNotFound);
 
-extern int TwoPhaseRecoverMirror(void);
-
 extern void TwoPhaseAddPreparedTransactionInit(
 					        prepared_transaction_agg_state **ptas
 					      , int                             *maxCount);