ash: add most of hush process subst tests

ash passes these.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/ash_test/ash-psubst/tick.tests b/shell/ash_test/ash-psubst/tick.tests
new file mode 100755
index 0000000..1f749a9
--- /dev/null
+++ b/shell/ash_test/ash-psubst/tick.tests
@@ -0,0 +1,4 @@
+true
+false; echo `echo $?`
+true
+{ false; echo `echo $?`; }