afsd.fuse: Solaris 11 support

The FUSE in Solaris 11 has a couple of quirks; work around them.

Reviewed-on: http://gerrit.openafs.org/6421
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 98a6db0b047efcfbeb0fb3c8b1e4e136b206f10d)

Change-Id: I6036c6e599c1fe57bae79516cb4333219afd75cf
Reviewed-on: http://gerrit.openafs.org/9454
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>