[Users] heders in route & failure_route blocks

[Juha Heinanen]

JF writes:

 > Shouldn't the route block lumps be cleared in the faked_req when
 > calling fake_req() in modules/tm/t_reply.c ? This way in the failure
 > route only the lumps created there will be apllied...?

that change cannot be done, because it would break existing openser.cfg
files that assume that headers added in route blocks are also included
in failure_route blocks.   perhaps a function that clears all existing
lumps could be introduced.

-- juha