Allow NO_FOO to override WITH_FOO that could be specified in /etc/src.conf.
Allow NO_FOO to override WITH_FOO that could be specified in /etc/src.conf.

This is required to override knobs (e.g. WITH_PROFILE) during buildworld
stages in Makefile.inc1 (otherwise the build is stopped due to both WITH_FOO
and WITHOUT_FOO defined).

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase