fsx-mpi: fsx-mpi expects a file name not a dir

fsx-mpi: fsx-mpi expects a file name not a dir

The test still fails even after being enabled:

	2016-12-07T18:00:44.337 INFO:teuthology.orchestra.run.mira105:Running: 'mpiexec -f /home/ubuntu/cephtest/mpi-hosts -wdir /home/ubuntu/cephtest/gmnt sudo /home/ubuntu/cephtest/fsx-mpi -o 1MB -N 50000 -p 10000 -l 1048576 /home/ubuntu/cephtest/gmnt/test'
	2016-12-07T18:00:44.486 INFO:teuthology.orchestra.run.mira105.stderr:Warning: Permanently added '172.21.8.122' (ECDSA) to the list of known hosts.
	2016-12-07T18:00:44.571 INFO:teuthology.orchestra.run.mira105.stdout:skipping zero size read
	2016-12-07T18:00:44.591 INFO:teuthology.orchestra.run.mira105.stdout:truncating to largest ever: 0x7cccb
	2016-12-07T18:00:44.606 INFO:teuthology.orchestra.run.mira083:Running: 'sudo logrotate /etc/logrotate.d/ceph-test.conf'
	2016-12-07T18:00:44.611 INFO:teuthology.orchestra.run.mira100:Running: 'sudo logrotate /etc/logrotate.d/ceph-test.conf'
	2016-12-07T18:00:44.614 INFO:teuthology.orchestra.run.mira105:Running: 'sudo logrotate /etc/logrotate.d/ceph-test.conf'
	2016-12-07T18:00:44.887 INFO:teuthology.orchestra.run.mira105.stdout:skipping zero size read
	2016-12-07T18:00:44.954 INFO:teuthology.orchestra.run.mira105.stdout:Size error: expected 0xa6f7c stat 0xd4000 seek 0xd5000
	2016-12-07T18:00:44.954 INFO:teuthology.orchestra.run.mira105.stdout:LOG DUMP (2 total operations):
	2016-12-07T18:00:44.954 INFO:teuthology.orchestra.run.mira105.stdout:1(1 mod 256): SKIPPED (no operation)
	2016-12-07T18:00:44.954 INFO:teuthology.orchestra.run.mira105.stdout:2(2 mod 256): WRITE        0x1c748 thru 0xa6f7b    (0x8a834 bytes) HOLE
	2016-12-07T18:00:44.990 INFO:teuthology.orchestra.run.mira105.stdout:Correct content saved for comparison
	2016-12-07T18:00:44.990 INFO:teuthology.orchestra.run.mira105.stdout:(maybe hexdump "/home/ubuntu/cephtest/gmnt/test" vs "/home/ubuntu/cephtest/gmnt/test.fsxgood")
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stdout:
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stdout:===================================================================================
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stdout:=   BAD TERMINATION OF ONE OF YOUR APPLICATION PROCESSES
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stdout:=   EXIT CODE: 120
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stdout:=   CLEANING UP REMAINING PROCESSES
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stdout:=   YOU CAN IGNORE THE BELOW CLEANUP MESSAGES
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stdout:===================================================================================
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stderr:[proxy:0:0@mira105] HYD_pmcd_pmip_control_cmd_cb (./pm/pmiserv/pmip_cb.c:886): assert (!closed) failed
	2016-12-07T18:00:45.000 INFO:teuthology.orchestra.run.mira105.stderr:[proxy:0:0@mira105] HYDT_dmxu_poll_wait_for_event (./tools/demux/demux_poll.c:77): callback returned error status
	2016-12-07T18:00:45.001 INFO:teuthology.orchestra.run.mira105.stderr:[proxy:0:0@mira105] main (./pm/pmiserv/pmip.c:206): demux engine error waiting for event
	2016-12-07T18:00:45.002 INFO:teuthology.orchestra.run.mira105.stderr:[mpiexec@mira105] HYDT_bscu_wait_for_completion (./tools/bootstrap/utils/bscu_wait.c:76): one of the processes terminated badly; aborting
	2016-12-07T18:00:45.002 INFO:teuthology.orchestra.run.mira105.stderr:[mpiexec@mira105] HYDT_bsci_wait_for_completion (./tools/bootstrap/src/bsci_wait.c:23): launcher returned error waiting for completion
	2016-12-07T18:00:45.002 INFO:teuthology.orchestra.run.mira105.stderr:[mpiexec@mira105] HYD_pmci_wait_for_completion (./pm/pmiserv/pmiserv_pmci.c:217): launcher returned error waiting for completion
	2016-12-07T18:00:45.002 INFO:teuthology.orchestra.run.mira105.stderr:[mpiexec@mira105] main (./ui/mpich/mpiexec.c:331): process manager error waiting for completion

I am not sure what the cause is. I'm leaving the test disabled for now and merging this PR.

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>