busybox: add some ignore files.

N/A

Signed-off-by: liminghao <liminghao@xiaomi.com>
busybox: config busybox and add some generated files.

N/A

1. $ make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- defconfig
2. $ make -n ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi-
3. According to make log build Gotoos.mk.

Signed-off-by: liminghao <liminghao@xiaomi.com>
busybox: add Gotoos.mk for busybox.

N/A

Signed-off-by: liminghao <liminghao@xiaomi.com>