OPTIMIZE TABLE against MyISAM/Aria table may fail and leave stale temporary file
if mysql_file_create() returns 0 file descriptor. This was due to wrong
condition, which considered 0 as failure.

5.5 doesn't have fix for MDEV-5679, thus 0 file descriptor is always occupied
by stdin and this bug is not reproducible.

10.1 has fix for MDEV-8475, which hides this bug.

No test case since it mostly depends on how OS returns file descriptors.