[PATCH] cleanup UFS swaplog messages

Inspired by bug 3663 - does not fix it, but then I'm not sure the report
is a squid bug or if it is regular filesystem permissions error.

This patch seeks to improve the messages output by UFS swap log
management. It also includes a small local variable symbol change from
"new_path" to "from_path" to prevent future developer mistakes like the
one seen in bug 3663 (mistaking "new_path" for the new destination path
of xrename() ).

Amos