Building rippled 1.3.1 requires gcc 7 or higher, but Ubuntu 16.04 ships with gcc 5.3.
To build rippled on Ubuntu 16.04, users will have to install gcc 7, possibly from a PPA. Investigate, test, and update the Ubuntu build instructions to call out the extra steps for building on Ubuntu 16.04, which AFAIK we'll continue to support until early 2021 since that's when Canonical's support transitions from "Maintenance updates" to "Extended security maintenance for customers"
Building
rippled
1.3.1 requires gcc 7 or higher, but Ubuntu 16.04 ships with gcc 5.3.To build rippled on Ubuntu 16.04, users will have to install gcc 7, possibly from a PPA. Investigate, test, and update the Ubuntu build instructions to call out the extra steps for building on Ubuntu 16.04, which AFAIK we'll continue to support until early 2021 since that's when Canonical's support transitions from "Maintenance updates" to "Extended security maintenance for customers"