patch 8.2.4539: when comparing special v:none and v:null are handled the same

Problem:    When comparing special v:none and v:null are handled the same when
            compiling.
Solution:   Pass more information so that v:none can be handled differently at
            compile time.  (issue #9923)
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 6a3c32a..25376d0 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -1799,7 +1799,7 @@
 		return FAIL;
 	    }
 	    type = get_type_on_stack(cctx, 0);
-	    if ((dest_type != VAR_BLOB && type != &t_special)
+	    if ((dest_type != VAR_BLOB && type->tt_type != VAR_SPECIAL)
 		    && need_type(type, &t_number,
 					    -1, 0, cctx, FALSE, FALSE) == FAIL)
 		return FAIL;