LINUX: fix array indexing issue in memory statistics

The comma is a sequence point and i gets incremented and then used.
This results in writing past the end of the array by one (and failing
to initialize the first element as well).

Potential fix for RT ticket 131566.

Reviewed-on: http://gerrit.openafs.org/8914
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Simon Wilkinson <simonxwilkinson@gmail.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 04ddecc1f2827463edf22857f9b19910ccc25e98)

Change-Id: I09a96fcb5ffc9a58f0930f76e4ee5f65628ba5c8
Reviewed-on: http://gerrit.openafs.org/9520
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>