fuse: sync fuse_kernel.h from linux 3.11.0(-rc3) header

The linux 3.11 fuse kernel header supports up through version 7.22.
Gluster has incrementally supported versions up to 7.22. This is a
hard sync of the most recent kernel header to resolve various,
minor descrepencies and facilitate updates going forward. The
following changes are included:

- Re-typed data structure definitions.
- Missing comments and init flag definitions (i.e., splice).
- Code format and whitespace differences.

No functional changes are included.

BUG: 990744
Change-Id: I86921ef7be56d31bab332cf8589262c2b9348221
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-on: http://review.gluster.org/5490
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>