Pass -Wno_undefined_callbacks to dialyzer on Erlang/OTP 17.

erlang:system_info(otp_release) now just returns the string "17". So
the regexp needed to be adjusted accordingly.

Change-Id: I3ae8c436d043a2917c5f882470dee401b814006d
Reviewed-on: http://review.couchbase.org/35711
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>