mount/fuse: enable fuse real async dio when available

fuse has support for optimized async. direct I/O handling via the
FUSE_ASYNC_DIO init flag. Enable FUSE_ASYNC_DIO when advertised
by fuse.

performance/write-behind: fix dio hang

Also fix a hang observed during aio-stress testing due to conflicting
request handling in write-behind. Overlapping requests are skipped
in pick_winds and may never continue when the conflicting write in
progress returns. Add a wb_process_queue() call after a non-wb request
completes to keep the queue moving.

BUG: 963258
Change-Id: Ifba6e8aba7a7790b288a32067706b75f263105d4
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-on: http://review.gluster.org/5014
Reviewed-by: Anand Avati <avati@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
tests: basic/rpm.t leaves /var/tmp/rpm-tests.* directories

When the test is terminated early because nothing changed that requires
this test, the /var/tmp/rpm-tests.xxxxxx is not removed.

BUG: 963333
Change-Id: I98d44ca34f14d62da9d836c41a9015cfb520ff96
Signed-off-by: Kaleb S. KEITHLEY <kkeithle@redhat.com>
Reviewed-on: http://review.gluster.org/5015
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>
tests: Ensure portmap registration before nfs mount.

Change-Id: I12a660a7dfbe4a2d0428910d762434043395fe02
BUG: 927616
Signed-off-by: Vijay Bellur <vbellur@redhat.com>
Reviewed-on: http://review.gluster.org/5012
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>