Simplify row_undo_ins_remove_sec_low()

Reduce the scope of some variables, remove a goto and a redundant
assertion.

For B-tree secondary indexes, this function can remove a delete-marked
purgeable record, in case a row rollback of the INSERT was initiated
due to an error in an earlier secondary index.

storage/innobase/row/row0uins.cc

 /*****************************************************************************
 
 Copyright (c) 1997, 2017, Oracle and/or its affiliates. All Rights Reserved.
-Copyright (c) 2017, 2018, MariaDB Corporation.
+Copyright (c) 2017, 2019, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -196,10 +196,8 @@ row_undo_ins_remove_sec_low(
 	que_thr_t*	thr)	/*!< in: query thread */
 {
 	btr_pcur_t		pcur;
-	btr_cur_t*		btr_cur;
 	dberr_t			err	= DB_SUCCESS;
 	mtr_t			mtr;
-	enum row_search_result	search_result;
 	const bool		modify_leaf = mode == BTR_MODIFY_LEAF;
 
 	row_mtr_start(&mtr, index, !modify_leaf);
@@ -224,12 +222,15 @@ row_undo_ins_remove_sec_low(
 		mode |= BTR_RTREE_UNDO_INS;
 	}
 
-	search_result = row_search_index_entry(index, entry, mode,
-					       &pcur, &mtr);
-
-	switch (search_result) {
+	switch (row_search_index_entry(index, entry, mode, &pcur, &mtr)) {
+	case ROW_BUFFERED:
+	case ROW_NOT_DELETED_REF:
+		/* These are invalid outcomes, because the mode passed
+		to row_search_index_entry() did not include any of the
+		flags BTR_INSERT, BTR_DELETE, or BTR_DELETE_MARK. */
+		ut_error;
 	case ROW_NOT_FOUND:
-		goto func_exit;
+		break;
 	case ROW_FOUND:
 		if (dict_index_is_spatial(index)
 		    && rec_get_deleted_flag(
@@ -239,31 +240,22 @@ row_undo_ins_remove_sec_low(
 				<< " is deleted marked on insert rollback.";
 			ut_ad(0);
 		}
-		break;
 
-	case ROW_BUFFERED:
-	case ROW_NOT_DELETED_REF:
-		/* These are invalid outcomes, because the mode passed
-		to row_search_index_entry() did not include any of the
-		flags BTR_INSERT, BTR_DELETE, or BTR_DELETE_MARK. */
-		ut_error;
-	}
-
-	btr_cur = btr_pcur_get_btr_cur(&pcur);
+		btr_cur_t* btr_cur = btr_pcur_get_btr_cur(&pcur);
 
-	if (modify_leaf) {
-		err = btr_cur_optimistic_delete(btr_cur, 0, &mtr)
-			? DB_SUCCESS : DB_FAIL;
-	} else {
-		/* Passing rollback=false here, because we are
-		deleting a secondary index record: the distinction
-		only matters when deleting a record that contains
-		externally stored columns. */
-		ut_ad(!dict_index_is_clust(index));
-		btr_cur_pessimistic_delete(&err, FALSE, btr_cur, 0,
-					   false, &mtr);
+		if (modify_leaf) {
+			err = btr_cur_optimistic_delete(btr_cur, 0, &mtr)
+				? DB_SUCCESS : DB_FAIL;
+		} else {
+			/* Passing rollback=false here, because we are
+			deleting a secondary index record: the distinction
+			only matters when deleting a record that contains
+			externally stored columns. */
+			btr_cur_pessimistic_delete(&err, FALSE, btr_cur, 0,
+						   false, &mtr);
+		}
 	}
-func_exit:
+
 	btr_pcur_close(&pcur);
 func_exit_no_pcur:
 	mtr_commit(&mtr);