Fix uninitialised value

[michaelortmann]

Found by: https://github.com/michaelortmann/
Patch by: https://github.com/michaelortmann/
Fixes:

One-line summary:

Additional description (if needed):

Test cases demonstrating functionality (if applicable):
> valgrind --track-origins=yes ./eggdrop -t BotA.conf
Then telnet to the bot

[...]
[06:40:18] Telnet connection: localhost.home.arpa/43372
==545660== Conditional jump or move depends on uninitialised value(s)
==545660==    at 0x402B970: dcc_telnet_hostresolved (dcc.c:1403)
==545660==    by 0x40300A2: dns_dcchostbyip (dns.c:164)
==545660==    by 0x4030CDA: call_hostbyip (dns.c:439)
==545660==    by 0x403F8EF: sockread (net.c:1067)
==545660==    by 0x403FC56: sockgets (net.c:1178)
==545660==    by 0x4036FB4: mainloop (main.c:765)
==545660==    by 0x4038305: main (main.c:1223)

==545660== Uninitialised value was created by a stack allocation
==545660== at 0x402B403: dcc_telnet_hostresolved (dcc.c:1318)
==545660==
[06:40:18] net: eof!(write) socket 11 (Broken pipe,32)
[06:40:18] EOF ident connection