Fix regression in openssl req -x509 behaviour.

Allow conversion of existing requests to certificates again.
Fixes the issue #3396

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from #3437)

apps/req.c

@@ -288,7 +288,6 @@ int req_main(int argc, char **argv)
             break;
         case OPT_X509:
             x509 = 1;
-            newreq = 1;
             break;
         case OPT_DAYS:
             days = atoi(opt_arg());
@@ -331,6 +330,9 @@ int req_main(int argc, char **argv)
     if (argc != 0)
         goto opthelp;
 
+    if (x509 && infile == NULL)
+        newreq = 1;
+
     /* TODO: simplify this as pkey is still always NULL here */
     private = newreq && (pkey == NULL) ? 1 : 0;
 
@@ -582,7 +584,7 @@ int req_main(int argc, char **argv)
         }
     }
 
-    if (newreq) {
+    if (newreq || x509) {
         if (pkey == NULL) {
             BIO_printf(bio_err, "you need to specify a private key\n");
             goto end;

doc/man1/req.pod

@@ -234,6 +234,9 @@ a self signed root CA. The extensions added to the certificate
 using the B<set_serial> option, a large random number will be used for
 the serial number.
 
+If existing request is specified with the B<-in> option, it is converted
+to the self signed certificate otherwise new request is created.
+
 =item B<-days n>
 
 When the B<-x509> option is being used this specifies the number of