Use afs_sfsize_t for *_SIZE results

Use afs_sfsize_t for *_SIZE results

Callers of FDH_SIZE and OS_SIZE should be storing the results in an
afs_sfsize_t. Some were using regular 'int's and other things, which
can screw up if the file is sufficiently large.

Change-Id: Ibbc2067ed3b90edcbdd46cfa43da559fd6419f0b
Reviewed-on: http://gerrit.openafs.org/2357
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>