Quick story short.
I'm running latest Linux Mint 18.2 and is still based on ubuntu Xenial.
To clean up my ssh configs I wanted to use new feature Include that was introduced in OpenSSH version 7.3.
Unfortunatelly there is an older version 7.2p2 in Xenial so decided to build the latest avaliable and that is 7.5p1.

First enable source repositories.list to be able to get some depedencies.

desktop ~ # apt-get install build-essential libgtk-3-dev devscripts
desktop ~ # apt-get build-dep openssh-server 

Get the sources and "borrow" some extra source packages from ubuntu artful

desktop ~ # mkdir /usr/src/openssh
desktop ~ # cd /usr/src/openssh
desktop openssh # wget http://piotrkosoft.net/pub/OpenBSD/OpenSSH/portable/openssh-7.5p1.tar.gz
desktop openssh # wget http://archive.ubuntu.com/ubuntu/pool/main/o/openssh/openssh_7.5p1.orig.tar.gz
desktop openssh # tar xf openssh-7.5p1.tar.gz
desktop openssh # cd openssh-7.5p1 
desktop openssh-7.5p1 # wget http://archive.ubuntu.com/ubuntu/pool/main/o/openssh/openssh_7.5p1-5ubuntu1.debian.tar.xz
desktop openssh-7.5p1 # tar xf openssh_7.5p1-5ubuntu1.debian.tar.xz

If all deps are fullfiled just build the deb packages:

desktop openssh-7.5p1 # debuild -us -uc -b
desktop openssh-7.5p1 # cd ..; ls *.deb
openssh-client_7.5p1-5ubuntu1_amd64.deb       openssh-server_7.5p1-5ubuntu1_amd64.deb       ssh_7.5p1-5ubuntu1_all.deb                  ssh-krb5_7.5p1-5ubuntu1_all.deb
openssh-client-ssh1_7.5p1-5ubuntu1_amd64.deb  openssh-sftp-server_7.5p1-5ubuntu1_amd64.deb  ssh-askpass-gnome_7.5p1-5ubuntu1_amd64.deb

Install and enjoy newest ssh!!

desktop openssh # dpkg -i openssh-client_7.5p1-5ubuntu1_amd64.deb openssh-server_7.5p1-5ubuntu1_amd64.deb ssh_7.5p1-5ubuntu1_all.deb ssh-askpass-gnome_7.5p1-5ubuntu1_amd64.deb ssh-krb5_7.5p1-5ubuntu1_all.deb
desktop openssh # ssh -V
OpenSSH_7.5p1 Ubuntu-5ubuntu1, OpenSSL 1.0.2g  1 Mar 2016