[PATCH] Add CONFIG_CHROMIUM option

[Matthew Wang]

Doh, you're right, I'll directly add to CFLAGS instead.

We have a couple patches that we maintain internally because we've
either tried to send them upstream and they've been rejected, or we
don't bother because they obviously won't be accepted. In particular,
there were some changes to the roaming heuristic I proposed a few
years ago that were rejected because they broke an hwsim test, but
we've been using them on ChromeOS anyway since they fixed a specific
enterprise customer's issue. Additionally, we currently carry around
an SSID pseudonymization patch to avoid storing PII in our logs. We
figured that if we could hide these behind a CHROMIUM flag, it would
make it easier for you to take them and easier for us to merge
upstream code into our tree due to fewer merge conflicts.