I've just committed some configuration changes that will make it easier to
experiment with the new ADB driver.  When you config(8) your kernel, a new
opt_mrg_adb.h header file will be created, so that make dependencies can
be generated and used to recompile only the affected code when the MRG_ADB
option is added or removed from your config file.

The short version:  You will have to re-run the config utility before you
can compile -current kernels, starting with the next SUP run.

--scott