update license of compat and crypto

- change license to be just MIT for all files in compat and crypto
- also add missing header end comments
- ensure default header include style
cleanup license and header end comment in chain.cpp/.h
Merge pull request #4990

7bec6dd cleanup license and header end comment in chain.cpp/.h (Philip Kaufmann)
0db65d8 update license of compat and crypto (Philip Kaufmann)