libusual: change block scope variable to function scope

Someone changed the code to kthread and used his style instead of mine.

The problem with the block variables is that they provoke shadowing,
which is actually exactly what has happened in my other tree which
has the class patch.

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>