The 'makeinfo' is required to generate the documentation from
the 'html' Makefile rule (called by 'install-doc').
The NSIS installer uses these files.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190715174817.18981-6-philmd@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>