Fix for bug #31781: multi-table UPDATE with temp-pool enabled fails                      with errno 17
Fix for bug #31781: multi-table UPDATE with temp-pool enabled fails 
                    with errno 17

my_create() did not perform any checks for the case when a file is
successfully created by a call to open(), but the call to
my_register_filename() later fails because the number of open files
has exceeded the my_open_files limit. This can happen on platforms 
which do not have getrlimit(), and hence we do not know the real limit
for open files. In such a case an error was returned to a caller
although the file has actually been created. Since callers assume
my_create() to return an error only when it failed to create a file,
they did not perform any cleanups, leaving an 'orphaned' file on the
file system.

Fixed by adding a check for the above case to my_create() and ensuring
the newly created file is deleted before returning an error.

Creating a deterministic test case in the test suite is impossible,
because the exact steps required to reproduce the above situation
depend on the platform and/or environment (OS per-user limits, queries
executed by previous tests, startup parameters). The patch was
manually tested on Windows using examples posted in the bug report.

ollie314/server,natsys/mariadb_10.2,ollie314/server,davidl-zend/zenddbi,davidl-zend/zenddbi,natsys/mariadb_10.2,davidl-zend/zenddbi,natsys/mariadb_10.2,davidl-zend/zenddbi,ollie314/server,ollie314/server,ollie314/server,ollie314/server,flynn1973/mariadb-aix,ollie314/server,natsys/mariadb_10.2,ollie314/server,flynn1973/mariadb-aix,ollie314/server,natsys/mariadb_10.2,slanterns/server,davidl-zend/zenddbi,davidl-zend/zenddbi,davidl-zend/zenddbi,natsys/mariadb_10.2,davidl-zend/zenddbi,flynn1973/mariadb-aix,davidl-zend/zenddbi,natsys/mariadb_10.2,flynn1973/mariadb-aix,flynn1973/mariadb-aix,flynn1973/mariadb-aix,natsys/mariadb_10.2,flynn1973/mariadb-aix,davidl-zend/zenddbi,natsys/mariadb_10.2,flynn1973/mariadb-aix,flynn1973/mariadb-aix,ollie314/server,davidl-zend/zenddbi,natsys/mariadb_10.2,flynn1973/mariadb-aix,natsys/mariadb_10.2,ollie314/server,flynn1973/mariadb-aix