Cleanup paths in pdns-recursor.init.d

prefix was unused, the others had a trailing slash, leading to process
command lines like "/usr/sbin//pdns_recursor".
Add exit codes to pdns-recursor init script

Fixes #676.
send empty SERVFAIL on exeeded retargetcount and log failures
update loop breakout test
Introduce makeUNsockaddr and have everybody use it

makeUNsockaddr does the length check in a central place, and calling
code should be a bit more readable now.
Merge pull request #987 from mind04/endless

send empty SERVFAIL on exeeded retargetcount and log failures
Merge pull request #976 from zeha/sockaddr_un

Introduce makeUNsockaddr and have everybody use it
Merge pull request #785 from zeha/f/init.d-fixup

Cleanup paths in pdns-recursor.init.d
Merge pull request #849 from zeha/f/issue-676

Add exit codes to pdns-recursor init script