Regression test portability: quota-anon-fd-nfs.t

Fix portability problems in quota-anon-fd-nfs.t
- Use mount_nfs wrapper and include nfs.rc to get it defined.
- umount NFS before cleanup to avvoid deadlocks.
- umount -l is Linux-specific, use umount -f on BSD.
- wait for 1s for portmap registration before mouting NFS.
- mount from $H0 instead of localhost: the later fails on NetBSD.
- Test quota without filling GB of data, 20MB is enough and it
  will be gentle with smaller setups.
- wait for write behind to complete before testing quota overflow

BUG: 1129939
Change-Id: I097d5faed2fa7b6438aaa56def85172f23bbe7dc
Signed-off-by: Emmanuel Dreyfus <manu@netbsd.org>
Reviewed-on: http://review.gluster.org/8969
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Kiran Patil <kiran@fractalio.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>