Load the ONE_SHOT_MAKEFILE even in dont_bother mode

This makes "mmm <path> snod" work again.
Note that snod has dependency on the rest of the command line goals,
which is all_modules for ONE_SHOT_MAKEFILE,
so build race condition is avoided.

Change-Id: Ib0c0e622530cde773180a095e5ec4dde1149b8e5