fix(ast): export/extern 变量 AnnAssign 固定 simple=1，Equal 判定显式 != 0

ast/parser.vp

@@ -3912,8 +3912,7 @@ def _parse_export_extern_var(ps: rawptr[Parser]) -> rawptr[AST]:
             return None
     target: rawptr[AST] = Name(ps.pool, name, ASTCtx.Store)
     _set_pos(target, lineno, col, 0, 0)
-    node: rawptr[AST] = AnnAssign(ps.pool, target, annotation, value,
-                                  1 if value is not None else 0)
+    node: rawptr[AST] = AnnAssign(ps.pool, target, annotation, value, 1)
     _set_pos(node, lineno, col, 0, 0)
     _skip_nl(ps)
     if _cur_type(ps) != TokenType.NewLine and _cur_type(ps) != TokenType.EndMarker: