xfstest 245: accept ENOTEMPTY as a valid error

xfstest 245: accept ENOTEMPTY as a valid error

Test 245 only checks to see if the rename returned EEXIST, but according to the
rename(2) manpage, ENOTEMPTY is also a valid result, which is in fact what Btrfs
returns.  So just filter the output for ENOTEMPTY so that either EEXIST or
ENOTEMPTY will pass the test.  It's not pretty I know, but I couldn't really
figure out a good way to get an either/or output to compare.  With this fix
Btrfs now passes 245.

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>