chroot: git-core search is failing on debian, just look for /usr/bin/git and stop build on failure

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
wheezy: use git over https: error: Problem with the SSL CA cert (path? access rights?)

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
rcn: use any of these

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