Add CC0 copyright statement to EIPs part of previous hard forks

[axic]

Partially-fixes #2062.

Please, everyone involved, approve this change (or make the change yourself in a new PR with a preferred license, if CC0 is not acceptable).

cc @vbuterin @holiman @ethers @chriseth @Souptacular @fjl @avsa @Arachnid

[axic]

Would appreciate a confirmation from @vbuterin @ethers @chriseth @Souptacular @avsa @Arachnid

[Souptacular]

I approve!

[ethers]

approve. thanks

[eip-automerger]

Hi! I'm a bot, and I wanted to automerge your PR, but couldn't because of the following issue(s):

• EIP 100 is in state Final, not Draft or Last Call
• EIP 1014 is in state Final, not Draft or Last Call
• EIP 137 is in state Final, not Draft or Last Call
• EIP 150 is in state Final, not Draft or Last Call
• EIP 155 is in state Final, not Draft or Last Call
• EIP 158 is in state Superseded, not Draft or Last Call
• EIP 160 is in state Final, not Draft or Last Call
• EIP 170 is in state Final, not Draft or Last Call
• EIP 2 is in state Final, not Draft or Last Call
• EIP 3 is in state Abandoned, not Draft or Last Call
• EIP 4 is in state Superseded, not Draft or Last Call
• EIP 5 is in state Superseded, not Draft or Last Call
• EIP 55 is in state Final, not Draft or Last Call
• EIP 6 is in state Final, not Draft or Last Call
• EIP 7 is in state Final, not Draft or Last Call
• EIP 101 requires approval from one of (v@buterin.com)
• EIP 210 requires approval from one of (@vbuterin)

[github-actions]

There has been no activity on this pull request for two months. It will be closed in a week if no further activity occurs. If you would like to move this EIP forward, please respond to any outstanding feedback or add a comment indicating that you have addressed all required feedback and are ready for a review.

[axic]

I think we need to split this so that those who accepted it can be merged, while we keep pinging the others.

[github-actions]

This pull request was closed due to inactivity. If you are still pursuing it, feel free to reopen it and respond to any feedback or request a review in a comment.