[eigen] MPL2 relicensing: tracking 3rd-party code

[Benoit Jacob <jacob.benoit.1@xxxxxxxxx>]

(Daniel: questions for you below, see (*) marks).

Hi,

So the relicensing effort is going really well:
 - as of today we have the answers to the big questions about the
MPL2, about GPL compatibility etc. See other threads.
 - the chasing down of contributors to get their approval is under
way, in another thread.

Now the biggest remaining problem is 3rd-party code.

First questions:

(*) How much does it actually matter that all the 3rdparty code we use
is MPL2, is it acceptable to have 3rdparty code under BSD/MIT, and is
it acceptable to have some LGPLv3 code under Section 3 of the LGPLv3
as it's headers?

So, the next steps (looking for volunteers)

 - establish a list of all the 3rd party code we have. Is there a
rational way of finding all of it at once?

 - track down their copyright holders, contact them

 - for the code that we won't get allowed to relicense, we could still
keep it and create a EIGEN_MPL2_ONLY mode where all the non-MPL2 code
would be disabled. Question:

(*) Would BSD/MIT 3rd-party code then have to be disabled in
EIGEN_MPL2_ONLY mode?

Cheers,
Benoit