patch 8.2.2485: when sourcing a script again the script version isn't reset

Problem:    When sourcing a script again the script version isn't reset.
Solution:   Set sn_version to one when sourcing a script again. Clear
            sn_save_cpo properly. (closes #7608)
diff --git a/src/scriptfile.c b/src/scriptfile.c
index c8a23d5..82ae42a 100644
--- a/src/scriptfile.c
+++ b/src/scriptfile.c
@@ -1319,6 +1319,9 @@
 	    }
 	// imports can be redefined once
 	mark_imports_for_reload(sid);
+
+	// reset version, "vim9script" may have been added or removed.
+	si->sn_version = 1;
     }
     else
     {
@@ -1457,7 +1460,7 @@
     if (si->sn_save_cpo != NULL)
     {
 	set_option_value((char_u *)"cpo", 0L, si->sn_save_cpo, 0);
-	CLEAR_POINTER(si->sn_save_cpo);
+	VIM_CLEAR(si->sn_save_cpo);
     }
 
     restore_funccal();