patch 8.2.1091: no check if opening a pty works

Problem:    No check if opening a pty works.
Solution:   Check for invalid file descriptor.

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1091,
 /**/
     1090,
 /**/