patch 8.1.0451: Win32 console: keypad keys don't work

Problem:    Win32 console: keypad keys don't work.
Solution:   Use numbers instead of characters to avoid the value becoming
            negative. (Mike Williams)

src/version.c

@@ -792,6 +792,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    451,
 /**/
     450,
 /**/