syslogd: fix memory leaks in main(..) and allowaddr(..)

• main(..): free memory assigned to fdsr before calling die(..).
• allowaddr(..): free memory assigned to ap before returning from the function early. Add a err goto label to reduce freeaddrinfo/free(ap) logic duplication.

MFC after: 1 week
X-MFC notes: some of this is dependent on refactoring not MFCed
Reported by: clang static analyzer, Coverity
CID: 1367750 (ap leakage in allowaddr(..))
Submitted by: Tom Rix <trix@juniper.net>
Reviewed by: ngie
Sponsored by: Dell EMC Isilon, Juniper
Differential Revision: D10004