Fixing ubuntu installation description

[dr-orlovsky]

Adding required libssl-dev to Ubuntu installation guide section and adding details for BerkleyDB installation

[hebasto]

This duplicates https://github.com/bitcoin/bitcoin/blob/master/doc/build-unix.md#berkeley-db

[hebasto]

@dr-orlovsky

Welcome!

Adding required libssl-dev to Ubuntu installation guide section...

Why do you think libssl-dev is required? Have you encountered a build issue?

[dr-orlovsky]

Thanks!

Yes, there was a build error on a clear Ubuntu 18.0.4 (bionic) machine during .configure:

checking for SSL... no
configure: error: openssl not found.

It seems it was shipped previously with Ubuntu and now is not.

[fanquake]

checking for SSL... no

OpenSSL is no longer required after #17265. What version of Bitcoin Core are you building?

[dr-orlovsky]

v0.19.0.1 by checking out the tag:

/usr/local/src/bitcoin$ git status
HEAD detached at v0.19.0.1

[fanquake]

v0.19.0.1 by checkout out the tag:

In that case you should be looking at the docs in the 0.19 branch. The Linux instructions there still correctly list libssl-dev as required.

[dr-orlovsky]

Right, sorry, read them through github and have not paid attention to the branch/tag, thinking that v0.19.0.1 is a very recent release and there were no dramatic changes after :)