add setup_env crosstool, and linux-bsp for bootstrap, u-boot, linux kernel

guowenxue

2019-08-05 8105b7510a3b06e208fbc46d8a329a750db014b6

linux-bsp/tarballs/linux-at91.tar.xz does not exist in tree b3a0e722ba54727b50b2a99c80e4607e69ba7e10