I don't know why fdt, Flat Device Tree, is disabled,
but that disabling blocks building e.g. qemu-system-aarch64.
It stops the build and yields this:
ERROR: fdt disabled but some requested targets require it.
You can turn off fdt only if you also disable all the system
emulation targets which need it
(by specifying a cut down --target-list).
Signed-off-by: Geert Stappers <stappers@stappers.it>