STR(SMTP_PORT) returns "SMTP_PORT", not "25"

SMTP client is broken in keepalived 1.2.14:
```
Keepalived_healthcheckers[14971]: Timeout reading data to remote SMTP server [192.168.0.1]:0
```

Wrong argument is passed to inet_stosockaddr() in smtpip_handler():
```
Breakpoint 1, inet_stosockaddr (ip=0x7f81618e5c50 "192.168.0.1", port=0x7f81600ebc6e "SMTP_PORT", addr=0x7f81618e35e0) at utils.c:164
```