loader.efi still needs work, but boot1.efi now builds.
Differential Revision: https://reviews.freebsd.org/D2244
Reviewed by: rpaulo
Sponsored by: The FreeBSD Foundation
support for booting arm and arm64 from UEFI.
Differential Revision: https://reviews.freebsd.org/D2164
Reviewed by: emaste, imp (previous version)
Sponsored by: The FreeBSD Foundation