MINOR: sink: Set the default max length for a message to BUFSIZE

It was set to MAX_SYSLOG_LEN (1K). It is a bit short to print debug
traces. Especially when part of a buffers is dump. Now, the maximum length is
set to BUFSIZE (16K).
diff --git a/src/sink.c b/src/sink.c
index 1d30f63..72e1743 100644
--- a/src/sink.c
+++ b/src/sink.c
@@ -65,7 +65,7 @@
 	/* set defaults for syslog ones */
 	sink->syslog_facility = 0;
 	sink->syslog_minlvl   = 0;
-	sink->maxlen = MAX_SYSLOG_LEN;
+	sink->maxlen = BUFSIZE;
 	/* address will be filled by the caller if needed */
 	sink->ctx.fd = -1;
 	sink->ctx.dropped = 0;