Remove unneeded null pointer checks before PQfreemem()

PQfreemem() just calls free(), and the latter already checks for null
pointers.

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://www.postgresql.org/message-id/flat/cf26e970-8e92-59f1-247a-aa265235075b%40enterprisedb.com

contrib/vacuumlo/vacuumlo.c

@@ -231,11 +231,8 @@ vacuumlo(const char *database, const struct _param *param)
 			pg_log_error("%s", PQerrorMessage(conn));
 			PQclear(res);
 			PQfinish(conn);
-			if (schema != NULL)
 			PQfreemem(schema);
-			if (table != NULL)
 			PQfreemem(table);
-			if (field != NULL)
 			PQfreemem(field);
 			return -1;
 		}

src/backend/replication/libpqwalreceiver/libpqwalreceiver.c

@@ -741,7 +741,6 @@ static void
 libpqrcv_disconnect(WalReceiverConn *conn)
 {
 	PQfinish(conn->streamConn);
-	if (conn->recvBuf != NULL)
 	PQfreemem(conn->recvBuf);
 	pfree(conn);
 }
@@ -768,7 +767,6 @@ libpqrcv_receive(WalReceiverConn *conn, char **buffer,
 {
 	int			rawlen;
 
-	if (conn->recvBuf != NULL)
 	PQfreemem(conn->recvBuf);
 	conn->recvBuf = NULL;
 

src/bin/pg_basebackup/receivelog.c

@@ -858,7 +858,6 @@ HandleCopyStream(PGconn *conn, StreamCtl *stream,
 	}
 
 error:
-	if (copybuf != NULL)
 	PQfreemem(copybuf);
 	return NULL;
 }
@@ -940,7 +939,6 @@ CopyStreamReceive(PGconn *conn, long timeout, pgsocket stop_socket,
 	char	   *copybuf = NULL;
 	int			rawlen;
 
-	if (*buffer != NULL)
 	PQfreemem(*buffer);
 	*buffer = NULL;
 
@@ -1204,7 +1202,6 @@ HandleEndOfCopyStream(PGconn *conn, StreamCtl *stream, char *copybuf,
 		}
 		still_sending = false;
 	}
-	if (copybuf != NULL)
 	PQfreemem(copybuf);
 	*stoppos = blockpos;
 	return res;