patch 8.2.1644: Vim9: cannot assign 1 and 0 to bool at script level

Problem:    Vim9: cannot assign 1 and 0 to bool at script level.
Solution:   Add the TTFLAG_BOOL_OK flag to the type. Fix name of test
            function.

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1644,
 /**/
     1643,
 /**/