[SSSD] [PATCH] NSS: Fix off-by-one error in parse_getservbyname

[Jakub Hrozek]

https://fedorahosted.org/sssd/ticket/1438

This off-by-one bug would hit us especially when using the negative
cache, I guess it was because we would strdup and later retrieve
something else than intended..

The same bug does not exist in the similar parse_getservbyport function.

I managed to reproduce the bug with by queriying the SSSD for services
quite fast. The services/protocols were based on data from the crash
dump:

for s in smtp/dccp  rpcbind/dccp  rpcbind/udplite  rpcbind/sctp
rpcbind/sctp  47117/udp  rpcbind/dccp; do getent services $s; sleep 1;
done