"Build at once" broken

[MatthewLCreech at eaton.com]

I'm not sure if this is known and was accidentally left in the config,
or if nobody has noticed yet, but the "build all sources at once" option
is currently broken.  I noticed when updating from 1.2.2.1 to 1.3.1, as
I enabled CONFIG_BUILD_AT_ONCE in the config, but BusyBox was still
built in pieces.

The offending change seems to be 16307, which removes pertinent code
from the top-level Makefile.  Just FYI

-- 
Matthew L. Creech