o This is disabled by default for now, and can be enabled using WITH_FDT at
build time.
o Tested with ARM and PowerPC.
Reviewed by: imp
Sponsored by: The FreeBSD Foundation
o Move the API prototypes to a separate header (glue.h)
o Allow the platform to hint libuboot about where to look
for the API signature. The uboot_address variable is
expected to be defined by the platform.