Ignore return values harder

Ignore return values harder

In various places where we intentionally ignore the return values of system
calls and standard library routines, this changes the way in which we do so,
to avoid compiler warnings when building on Ubuntu 12.10, with gcc 4.7.2 and
eglibc 2.15-0ubuntu20.1.

Reviewed-on: http://gerrit.openafs.org/9980
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 73cad3be0a3489237ab7e66d3b12c52ffb0b67d0)

Change-Id: I934406d67d7409655a7084894fd231c410d72c58
Reviewed-on: http://gerrit.openafs.org/11715
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: Daria Phoebe Brashear <shadow@your-file-system.com>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>