Allow BASE_RUN_SMOKE to be overridden by localrc

Currently, only TARGET_RUN_SMOKE is allowed to be overridden
by the user/gate while BASE_RUN_SMOKE is ignored if set via
localrc.  This updates grenaderc and matches the expected defaults
and overrides.

Change-Id: I3e74e53e697c4774a24ec86a1698072705509c06