Based on Googling, one of the best lint tools for Cpp is a Clang-Tidy. It provides framework for diagnosing style violations, interface misuse and bugs that can be deduced via static analysis. Google C++ Testing Framework is a popular xUnit architecture based testing library. For building I would use cMake. It is a simple, open-source cross-platform family of tools.
Some other tools for CI include Buddy, TeamCity and GoCD. Buddy should be easy to configure, fast to deploy and support all popular languages and frameworks. TeamCity should have extensibility and customization, as well as provide better code quality. It integrates your building and testing tools and visualizes DevOps pipelines. GoCD is used to model and visualize complex workflows and allows continuous delivery and intuitive interface.
Buddy was released as a cloud-only service. It is supposed to be an easy-to use tool to lower the entry threshold to DevOps and it is mainly used for small projects. So Buddy is a cloud based option for CI. However, there is also Buddy GO, a docker-based CI server with git hosting. This allows to use Buddy behing your own firewall. Because Buddy is originally a cloud based service, it is what it does best and I would use Buddy for a semi-small, cloud based projects.