travis.yml: Move gprof/gcov test across to gitlab

Similarly to commit 8cdb2cef, move the gprof/gcov test to GitLab.

The coverage-summary.sh script is not Travis-CI specific, make it
generic.

[thuth: Add gcovr and bsdmainutils which are required for the
        coverage-summary.sh script to the ubuntu docker file,
        and use 'check' as test target]

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Message-Id: <20201108204535.2319870-10-philmd@redhat.com>
Message-Id: <20210211045455.456371-2-thuth@redhat.com>
Message-Id: <20210211122750.22645-2-alex.bennee@linaro.org>