coverity: fix memory leak in lldpcli

CID 1198257 (#1 of 1): Resource leak (RESOURCE_LEAK)
coverity: fix memory leak in lldpd when the same option is repeated
coverity: fix a false positive in SNMP transport

`remote` is not expected to be a NULL-terminated string. However, just
in case it is used as one somewhere, we alloc the appropriate space for
it.