hush testsuite: add many tests from ash testsuite

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-signals/signal2.right b/shell/hush_test/hush-signals/signal2.right
new file mode 100644
index 0000000..a2af919
--- /dev/null
+++ b/shell/hush_test/hush-signals/signal2.right
@@ -0,0 +1,3 @@
+child sleeps
+child exits as expected
+parent exits