Dependencies for opensaml2 2.6.0-4 jessie backport

[Ferenc Wágner]

Etienne Dysli-Metref <etienne.dysli-metref at switch.ch> writes:

> + libxmltooling7 (>= 1.6.0-3~),

libxmltooling7 is not in jessie, so this isn't needed anywhere.
-- 
Feri