build: add profile-stats to extra-dist files

The profile-stats script must be distributed. This also solves a build
problem during the pep8 check (E902 IOError):

 [Errno 2] No such file or directory: 'contrib/profile-stats'

Change-Id: I75abc5faea205c959175736ca62684ac5b30d457
Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/27978
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>