This commit adds the basic support for HTTPBoot, i.e. to fetch
the next stage loader with the HTTP protocol.
It requires gnu-efi >= 3.0.3 to support the URI device path and
Ip4Config2 or Ip6Config protocol support in the UEFI implementation.
To build shim.efi with HTTPBoot support:
make ENABLE_HTTPBOOT=1 shim.efi
Signed-off-by: Gary Ching-Pang Lin <glin@suse.com>
