hush: "adopt" ash signal4.tests

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-signals/signal4.right b/shell/hush_test/hush-signals/signal4.right
new file mode 100644
index 0000000..2d06247
--- /dev/null
+++ b/shell/hush_test/hush-signals/signal4.right
@@ -0,0 +1,4 @@
+hush: trap: BADNAME: invalid signal specification
+1
+Trapped
+Ok