Fix/simplify setting of one Failed-AVP
Fix/simplify setting of one Failed-AVP

When setting the Result-Code/Failed-AVP of an outgoing answer from an
errors list either returned from or not discarded by a handle_request
callback, more than the AVP paired with the Result-Code in question
could be set in Failed-AVP.

RFC 6733:

7.5.  Failed-AVP AVP

   The Failed-AVP AVP (AVP Code 279) is of type Grouped and provides
   debugging information in cases where a request is rejected or not
   fully processed due to erroneous information in a specific AVP.  The
   value of the Result-Code AVP will provide information on the reason
   for the Failed-AVP AVP.  A Diameter answer message SHOULD contain an
   instance of the Failed-AVP AVP that corresponds to the error
   indicated by the Result-Code AVP.  For practical purposes, this
   Failed-AVP would typically refer to the first AVP processing error
   that a Diameter node encounters.

aboroska/otp,cobusc/otp,jj1bdx/otp,bernardd/otp,erlang/otp,erlang/otp,rlipscombe/otp,RaimoNiskanen/otp,isvilen/otp,goertzenator/otp,erlang/otp,dumbbell/otp,bjorng/otp,electricimp/otp,mikpe/otp,tuncer/otp,erlang/otp,vladdu/otp,vladdu/otp,dumbbell/otp,saleyn/otp,cobusc/otp,falkevik/otp,electricimp/otp,RaimoNiskanen/otp,saleyn/otp,g-andrade/otp,uabboli/otp,vladdu/otp,ferd/otp,vinoski/otp,mikpe/otp,getong/otp,potatosalad/otp,isvilen/otp,goertzenator/otp,RoadRunnr/otp,uabboli/otp,legoscia/otp,matwey/otp,bjorng/otp,vladdu/otp,rlipscombe/otp,vinoski/otp,ferd/otp,bsmr-erlang/otp,kvakvs/otp,legoscia/otp,dgud/otp,cobusc/otp,lrascao/otp,g-andrade/otp,lrascao/otp,legoscia/otp,rlipscombe/otp,dgud/otp,legoscia/otp,emacsmirror/erlang,bernardd/otp,potatosalad/otp,bjorng/otp,RaimoNiskanen/otp,dumbbell/otp,RaimoNiskanen/otp,kvakvs/otp,getong/otp,dgud/otp,aboroska/otp,RoadRunnr/otp,lrascao/otp,dumbbell/otp,bernardd/otp,tuncer/otp,bsmr-erlang/otp,cobusc/otp,RaimoNiskanen/otp,goertzenator/otp,rlipscombe/otp,emacsmirror/erlang,RoadRunnr/otp,kvakvs/otp,ferd/otp,goertzenator/otp,dgud/otp,potatosalad/otp,lrascao/otp,g-andrade/otp,matwey/otp,potatosalad/otp,lrascao/otp,ferd/otp,RoadRunnr/otp,erlang/otp,cobusc/otp,cobusc/otp,potatosalad/otp,kvakvs/otp,g-andrade/otp,RaimoNiskanen/otp,mikpe/otp,g-andrade/otp,falkevik/otp,rlipscombe/otp,bernardd/otp,vladdu/otp,falkevik/otp,emacsmirror/erlang,emacsmirror/erlang,cobusc/otp,rlipscombe/otp,falkevik/otp,bsmr-erlang/otp,fenollp/otp,fenollp/otp,kvakvs/otp,saleyn/otp,mikpe/otp,legoscia/otp,mikpe/otp,dumbbell/otp,dgud/otp,cobusc/otp,jj1bdx/otp,falkevik/otp,RoadRunnr/otp,fenollp/otp,bjorng/otp,isvilen/otp,goertzenator/otp,electricimp/otp,emacsmirror/erlang,getong/otp,bjorng/otp,uabboli/otp,getong/otp,falkevik/otp,mikpe/otp,bjorng/otp,lrascao/otp,aboroska/otp,goertzenator/otp,isvilen/otp,bjorng/otp,uabboli/otp,dgud/otp,fenollp/otp,ferd/otp,electricimp/otp,matwey/otp,saleyn/otp,isvilen/otp,aboroska/otp,jj1bdx/otp,dumbbell/otp,kvakvs/otp,jj1bdx/otp,saleyn/otp,electricimp/otp,potatosalad/otp,fenollp/otp,g-andrade/otp,erlang/otp,ferd/otp,matwey/otp,RoadRunnr/otp,tuncer/otp,falkevik/otp,legoscia/otp,electricimp/otp,saleyn/otp,bjorng/otp,jj1bdx/otp,uabboli/otp,goertzenator/otp,emacsmirror/erlang,erlang/otp,dumbbell/otp,uabboli/otp,lrascao/otp,matwey/otp,ferd/otp,electricimp/otp,getong/otp,fenollp/otp,kvakvs/otp,vladdu/otp,lrascao/otp,kvakvs/otp,jj1bdx/otp,dumbbell/otp,mikpe/otp,bsmr-erlang/otp,uabboli/otp,jj1bdx/otp,g-andrade/otp,fenollp/otp,g-andrade/otp,tuncer/otp,matwey/otp,rlipscombe/otp,potatosalad/otp,vinoski/otp,dgud/otp,matwey/otp,vinoski/otp,saleyn/otp,isvilen/otp,g-andrade/otp,bsmr-erlang/otp,vinoski/otp,bernardd/otp,vinoski/otp,aboroska/otp,emacsmirror/erlang,dgud/otp,uabboli/otp,goertzenator/otp,tuncer/otp,g-andrade/otp,fenollp/otp,mikpe/otp,goertzenator/otp,lrascao/otp,getong/otp,aboroska/otp,ferd/otp,isvilen/otp,isvilen/otp,RoadRunnr/otp,jj1bdx/otp,electricimp/otp,tuncer/otp,aboroska/otp,RoadRunnr/otp,RaimoNiskanen/otp,vinoski/otp,bjorng/otp,bjorng/otp,saleyn/otp,erlang/otp,jj1bdx/otp,vladdu/otp,tuncer/otp,emacsmirror/erlang,bsmr-erlang/otp,dgud/otp,potatosalad/otp,rlipscombe/otp,falkevik/otp,matwey/otp,tuncer/otp,falkevik/otp,vladdu/otp,erlang/otp,RoadRunnr/otp,jj1bdx/otp,vinoski/otp,vladdu/otp,tuncer/otp,getong/otp,mikpe/otp,rlipscombe/otp,aboroska/otp,dumbbell/otp,potatosalad/otp,vinoski/otp,getong/otp,emacsmirror/erlang,dgud/otp,bernardd/otp,legoscia/otp,RaimoNiskanen/otp,bsmr-erlang/otp,electricimp/otp,getong/otp,bernardd/otp,erlang/otp,kvakvs/otp,ferd/otp,potatosalad/otp,RaimoNiskanen/otp,getong/otp,matwey/otp,bsmr-erlang/otp,uabboli/otp,legoscia/otp,saleyn/otp,bernardd/otp,bsmr-erlang/otp,isvilen/otp,vinoski/otp,fenollp/otp,rlipscombe/otp,emacsmirror/erlang,dumbbell/otp,bernardd/otp,isvilen/otp,mikpe/otp,legoscia/otp,aboroska/otp