add simple xfs_fsr test

add simple xfs_fsr test

We have very little fsr test coverage in the test suite right now.
042 is the only test that runs it, and it only defragments a single
file.

Improve the coverage by simply running xfs_fsr of the test
filesystem. This gives xfs_fsr a wide variety of inodes to try to
defragment. A simple test like this would have tripped over the
attr2 fork offset problems in the swap extents ioctl long ago
thanks to the varied nature of inodes the test suite leaves around
in this filesystem.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>