hush: fix set -n to act immediately, not just after run_list()

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-misc/set-n1.tests b/shell/hush_test/hush-misc/set-n1.tests
new file mode 100755
index 0000000..90d0f91
--- /dev/null
+++ b/shell/hush_test/hush-misc/set-n1.tests
@@ -0,0 +1,2 @@
+$THIS_SH -c "echo 'set -n stops in -c?'; set -n; echo NO" && echo YES
+echo Ok:$?