[asterisk-dev] Bug fix for fxo modules to correctly detect answer/hangup when telco switches line reversal.

[Alec Davis]

Now that we have dahdi-linux-2.1.0 released can we get this into the trunk.

http://bugs.digium.com/view.php?id=13917

It has no impact on default setups where a channels have
answeronpolarityswitch=no or hanguponpolarityswitch=no.
It only comes into effect when a channel has answeronpolarityswitch=yes

This has succesfully be running without fault for nearly 2 months.

Alec Davis