ash : fix double-quoted "\z" handling

function                                             old     new   delta
readtoken1                                          2602    2608      +6

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-quoting/bkslash_case1.right b/shell/hush_test/hush-quoting/bkslash_case1.right
new file mode 100644
index 0000000..1b52491
--- /dev/null
+++ b/shell/hush_test/hush-quoting/bkslash_case1.right
@@ -0,0 +1,10 @@
+ok1
+ok2
+ok3
+ok4
+ok5
+Ok:0
+ok6
+ok7
+ok8
+Ok:0