afs: fs getcacheparms miscounts dcaches for large files

afs: fs getcacheparms miscounts dcaches for large files

fs getcacheparms issued with the -excessive option tabulates in-memory
dcaches ("DCentries") by size.  However, any dcache with validPos > 2^31
is miscounted in the 4k-16k bucket.  This is caused by a type mismatch
between 'validPos' (afs_size_t) and 'size' (int) which leads to a
negative value for size by sign-extension.  The size comparison "sieve"
fails for negative numbers; it skips the first bucket (0-4K) and dumps
them in the second one (4k-16k).

Move the declaration of 'size' closer to its use, and declare it with
the same type as 'validPos' (afs_size_t) so the comparison sieve
correctly places these dcaches in the last (>=1M) bucket.

Change-Id: Ib0d973da92865043a4f1c068de5e9b81bcde2b9a
Reviewed-on: https://gerrit.openafs.org/12347
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>