Why not AUTORECONF_FLAGS+= -f -i

We keep forcing -f -i because we always want that, but we allow the user to define its own flags before inclusion of the USES
at worst we will end up with duplicating -f and -i which I think is fine.

I would name the variable AUTORECONF_ARGS and put it after the -f -i here. Then document it above as "Extra arguments to autoreconf. Default: none". Then port maintainers can still pass --no-force or --no-install if needed and pass arguments other than flags such as a list of directories.