hush: add recent ash tests to hush testsuite too (they all pass for hush)

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-vars/var-do-not-collapse-arithmetic-expansion-at-parse-time.right b/shell/hush_test/hush-vars/var-do-not-collapse-arithmetic-expansion-at-parse-time.right
new file mode 100644
index 0000000..81a1585
--- /dev/null
+++ b/shell/hush_test/hush-vars/var-do-not-collapse-arithmetic-expansion-at-parse-time.right
@@ -0,0 +1,2 @@
+12
+9