MINOR: mailers: increase default timeout to 10 seconds

This allows the tcp connection to send multiple SYN packets, so 1 lost
packet does not cause the mail to be lost. It changes the socket timeout
from 2 to 10 seconds, this allows for 3 syn packets to be send and
waiting a little for their reply.

This patch should be backported to 1.6.

Acked-by: Simon Horman <horms@verge.net.au>
diff --git a/src/checks.c b/src/checks.c
index bc7eaa7..9d6d33e 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -3108,7 +3108,7 @@
 
 		LIST_INIT(&q->email_alerts);
 
-		check->inter = DEF_CHKINTR; /* XXX: Would like to Skip to the next alert, if any, ASAP.
+		check->inter = DEF_MAILALERTTIME; /* XXX: Would like to Skip to the next alert, if any, ASAP.
 					     * But need enough time so that timeouts don't occur
 					     * during tcp check procssing. For now just us an arbitrary default. */
 		check->rise = DEF_AGENT_RISETIME;