一、下载文件
expat下载目录：
https://github.com/libexpat/libexpat
dbus下载路径：
https://dbus.freedesktop.org/releases/dbus/
二、 交叉编译expat
./configure --prefix=/home/test/imx6ull-qt/dbus/target-expat --host=arm-linux-gnueabihf
make -j8
make install
三、交叉编译dbus
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/home/test/imx6ull-qt/dbus/target-expat/lib/pkgconfig
./configure --prefix=