libfuse: security bump to version 2.9.8

Fixes CVE-2018-10906 - In fuse before versions 2.9.8 and 3.x before 3.2.5,
fusermount is vulnerable to a restriction bypass when SELinux is active.
This allows non-root users to mount a FUSE file system with the
'allow_other' mount option regardless of whether 'user_allow_other' is set
in the fuse configuration.  An attacker may use this flaw to mount a FUSE
file system, accessible by other users, and trick them into accessing files
on that file system, possibly causing Denial of Service or other unspecified
effects.

And additionally:

- libfuse no longer segfaults when fuse_interrupted() is called outside the
  event loop.

- The fusermount binary has been hardened in several ways to reduce
  potential attack surface.  Most importantly, mountpoints and mount options
  must now match a hard-coded whitelist.  It is expected that this whitelist
  covers all regular use-cases.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>