patch 8.0.1820: terminal window redirecting stdout does not show stderr

Problem:    Terminal window redirecting stdout does not show stderr. (Matéo
            Zanibelli)
Solution:   When stdout is not connected to pty_master_fd then use it for
            stderr. (closes #2903)

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1820,
 /**/
     1819,
 /**/