cxxtest: new package

[Peter: fix toolchain comment, use INSTALL instead of mkdir/cp]
Reviewed-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Reviewed-by: Rahul Bedarkar <rahul.bedarkar@imgtec.com>
Reviewed-by: Piotr Nakraszewicz <piotr.nakraszewicz@imgtec.com>
Reviewed-by: Jerzy Grzegorek <jerzy.grzegorek@trzebnica.net>
Signed-off-by: Abhishek Singh <Abhishek.Singh@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>