icedtea-native from meta-java needs sha256sum for checksum validation.
Therefore add sha256sum to HOSTTOOLS (as md5sum is already in there).
Without it the icedtea-native build will fail during configuration at
current master.
Signed-off-by: Richard Leitner <richard.leitner@skidata.com> Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
