buildroot

gnuradio: add gr-ctrlport support

gr-ctrlport is a gnuradio module to create distributed control applications.

Signed-off-by: Gwenhael Goavec-Merou <gwenhael.goavec-merou@trabucayre.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>