add u-boot crosstool to fix u-boot can not build by buildroot crosstool 7.0...

guowenxue

2019-08-24 a6177b46d08f140c3287e79d4b99f78621ddfa5e

 3rdparty/dropbear/build.sh

@@ -11,7 +11,7 @@

LYFTP_SRC=ftp://master.iot-yun.club/src/

CROSSTOOL=/opt/crosstool/cortex-a7/bin/arm-linux-gnueabi-
CROSSTOOL=/opt/buildroot/cortex-a5/bin/arm-linux-

function msg_banner()
{
@@ -71,6 +71,7 @@
    PACK_SUFIX=tar.bz2

    if [ -f ${PREFIX_PATH}/bin/dropbear ] ; then
        msg_banner "$SRC_NAME already compile and installed"
        return 0;
    fi