patch 8.2.3276: Vim9: exists() can only be evaluated at runtime

Problem:    Vim9: exists() can only be evaluated at runtime.
Solution:   Evaluate at compile time for option name literals. (closes #8437)

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3276,
 /**/
     3275,
 /**/