Copy the new ia32 loader

This handles copying in install-boot.sh and bsdinstall's bootconfig.

install-boot.sh:
make_esp_file now optionally takes extra arguments so it can copy
multiple files. This is used by the amd64 release scripts.
make_esp_device also takes an extra optional argument for efibootname.
This is currently unused, but it can be used in the future to do
something like:
make_esp_device loader.efi bootx64
make_esp_device loader_ia32.efi bootia32

Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/1098