Add chown(), truncate, ftruncate, some xattr setting to racer.

file_rename.sh should use 'mv -T' as well as 'mv'.

mknod() is not used.

On my home setup I find that racer finds server-side bugs much faster if file_create.sh is modified to less IO per file.

There is some problem with running racer through autotest that needs to be understood. It seems not to start at all. Maybe someone knows what's going on and can comment.