I got much further by switching to Vagrant precise32 and installing the dependencies from the BSP guide. Now it's stopped the build here:
ERROR: Function failed: do_validate_branches (see /home/vagrant/galileo_build/meta-clanton_v1.0.0/yocto_build/tmp/work/clanton-poky-linux-uclibc/linux-yocto-clanton/3.8-r0/temp/log.do_validate_branches.27492 for further information)
ERROR: Logfile of failure stored in: /home/vagrant/galileo_build/meta-clanton_v1.0.0/yocto_build/tmp/work/clanton-poky-linux-uclibc/linux-yocto-clanton/3.8-r0/temp/log.do_validate_branches.27492
Log data follows:
| DEBUG: Executing shell function do_validate_branches
| Killed
| ERROR: Function failed: do_validate_branches (see /home/vagrant/galileo_build/meta-clanton_v1.0.0/yocto_build/tmp/work/clanton-poky-linux-uclibc/linux-yocto-clanton/3.8-r0/temp/log.do_validate_branches.27492 for further information)
ERROR: Task 236 (/home/vagrant/galileo_build/meta-clanton_v1.0.0/meta-clanton-bsp/recipes-kernel/linux/linux-yocto-clanton_3.8.bb, do_validate_branches) failed with exit code '1'
NOTE: Tasks Summary: Attempted 919 tasks of which 725 didn't need to be rerun and 1 failed.