This change extends the existing in-tree test infrastructure such
that it can also be run as part of a the installed package. This
simplifies testing on multiple systems and is generally all around
useful. The scripts may still be run in-tree and will use the
in-tree build products as long as .script-config exists.
SLES10 ships util-linux-2.12r-35.30 which does not support the -f option
to losetup. To avoid this problem the unused_loop_device() function was
added which attempts to find an unused loop device by checking each
/dev/loop* device with losetup to see if it is configured.
Brian Behlendorf