abuild: Allow disabling mainboards

There may be boards that shouldn't be built for one reason or another.
Allow black-listing them by adding a file to the mainboard directory called
'abuild.disabled'. It should contain the reason that is printed by abuild and
also serves as documentation for users that want to know what's going on.

Change-Id: I78c3281a578e96ee40f6b101143d4f3763582350
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-on: http://review.coreboot.org/10917
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
1 file changed