[asterisk-ss7] Error starting asterisk with libss7 support

[Andreas Kaufmann]

Hi Matthew,

unfortunately fixing the channel definition does not help. As soon as I 
turn on ss7 in zapata.conf the error message is shown.

I have tested different asterisk version, and I have found out that 
there is a version dependence. The error message does not appear with 
asterisk SVN-trunk-r117431, but with SVN-trunk-r118178 and also when 
using asterisk-1.6.0 branch.

Regards,
Andreas