ash,hush: testcase for "exit" without arguments in a trap

hush fails this one

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash_test/ash-misc/exitcode_trap2.right b/shell/ash_test/ash-misc/exitcode_trap2.right
new file mode 100644
index 0000000..6644d86
--- /dev/null
+++ b/shell/ash_test/ash-misc/exitcode_trap2.right
@@ -0,0 +1 @@
+42:42