fuse: Autodetect Solaris 11 FUSE

FUSE exists in Solaris 11, but it does not come with a fuse.pc
pkg-config configuration. Autodetect the presence of FUSE anyway.

Reviewed-on: http://gerrit.openafs.org/6422
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 2e5545342b0c644546f8a370bdbf836a6da68b60)

Change-Id: Ib9ef1702af1ff20d836b1c1649fc1182c93e209b
Reviewed-on: http://gerrit.openafs.org/9455
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>