xfsprogs: remove write-only assignments

xfsprogs: remove write-only assignments

There are many instances where variable assignments are made,
but never read (or are re-assigned before they are read).
The Clang static analyzer finds these.

Here's a chunk of what I think are trivial removals of such
assignments; other detections point to more serious problems
(or are shared w/ kernel code so should probably be fixed there
first).

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>