Merge #12278: Add special error for genesis coinbase to getrawtransaction

Summary:
PR12278 backport https://github.com/bitcoin/bitcoin/pull/12278/files
ee11121 Add special error for genesis coinbase to gettransaction (MeshCollider)

Pull request description:

Suggested by sipa here: https://botbot.me/freenode/bitcoin-core-dev/2018-01-23/?msg=96069825&page=2

Just adds a special error message for the genesis block coinbase transaction when using `getrawtransaction`

Test Plan:
make check
test_runner.py

Reviewers: jasonbcox, Fabien, #bitcoin_abc, deadalnix

Reviewed By: Fabien, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D3071