Merge pull request #2 from weinimo/master

Some fixes and updates for build.sh
gcc: use smaller xz releases from linaro

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
merge to: https://github.com/RobertCNelson/u-boot/commit/bbd0f7e3ba66d288a2f146f1c7797801e04598ae

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>