Squelch some warnings.

Make some arguments and structure members gsize, as that's what stored
into them or passed to them.  (And move a newly-widened-on-LP64 item, to
avoid extra structure padding.)

Add a cast, which also appears necessary to squelch a warning.

Clean up indentation while we're at it.

Change-Id: I0cc92e7d2904c5af1f3f3d93f51b6ecb3aed464d
Reviewed-on: https://code.wireshark.org/review/2741
Reviewed-by: Guy Harris <guy@alum.mit.edu>