libunistring recipe is needed by guile.
And guile is needed by autogen.
(From OE-Core rev: b9006a6fe807f6717fd6ee7237b23987184d2316)
Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>