Remove log record terminating null char before processing log lines.

Fix the end of log record pointer to not include the record
terminating null char. This caused the null to be part of the captured
fragments and sent to the output.

Fixes: #1382

bin/varnishncsa/varnishncsa.c

@@ -746,6 +746,8 @@ dispatch_f(struct VSL_data *vsl, struct VSL_transaction * const pt[],
 			tag = VSL_TAG(t->c->rec.ptr);
 			b = VSL_CDATA(t->c->rec.ptr);
 			e = b + VSL_LEN(t->c->rec.ptr);
+			while (e > b && e[-1] == '\0')
+				e--;
 
 			switch (tag) {
 			case SLT_ReqStart: