hush: make ${#var} unicode-aware

This mimics bash

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-misc/unicode1.right b/shell/hush_test/hush-misc/unicode1.right
new file mode 100644
index 0000000..d3bbbf6
--- /dev/null
+++ b/shell/hush_test/hush-misc/unicode1.right
@@ -0,0 +1,3 @@
+1
+1
+Ok