Fix inclusion of packaging/distinfo into make dist

This was placing distinfo as distinfo/distinfo.

Change-Id: Ic514c8874ff32f85e8120f8ffe21828ac4ec601a
Reviewed-on: http://review.couchbase.org/44491
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>