REGTESTS: 4be_1srv_smtpchk_httpchk_layer47errors: Return valid SMTP replies

The s1 server is acting like a SMTP server. But it sends two CRLF at the end of
each line, while only one CRLF must be returned. It only works becaue both CRLF
are received at the same time.

reg-tests/checks/4be_1srv_smtpchk_httpchk_layer47errors.vtc

@@ -36,12 +36,12 @@ server s1 {
     send "2"
     send "2"
     send "0"
-    send "\r\n\r\n"
+    send "\r\n"
     recv 16
     send "2"
     send "4"
     send "8"
-    send "\r\n\r\n"
+    send "\r\n"
 } -start
 
 server s2 {