BUG#13050593 - BACKSLASH SWALLOWED BY INCLUDE/SHOW_SLAVE_STATUS.INC

If an error message contains '\' backslash it is displayed correctly
through show-slave-status or
query_get_value(SHOW SLAVE STATUS, Last_IO_Error, 1);. But when
SELECT REPLACE(...) is applied backslash is escaped resulting in a
different test output.

Disabled backslash escape on show_slave_status.inc and replaced '\' for
'/' using replace_regex function in order to achieve the same test
output when different path separators are used.

mysql-test/include/wait_for_slave_io_error.inc

@@ -76,6 +76,7 @@ if ($show_slave_io_error)
 {
   --let $_wait_for_slave_io_error_old_status_items= $status_items
   --let $status_items= Last_IO_Error
+  --let $slave_field_result_replace= $slave_io_error_replace
   --source include/show_slave_status.inc
   --let $status_items= $_wait_for_slave_io_error_old_status_items
 }