[Makefile] find correct lablgtk2 init
[paparazzicenter] also check PRINT_CONFIG for upload button
[Makefile] ground_segment.opt target to build native gcs/server
[rotorcraft] fix FAILSAFE vertical setpoint

This was a regression, thx Michal for catching this!!
The vertical speed setpoint was set to 0.5m/s descent rate, but upon
guidance_v_mode_changed it was set back to zero so FAILSAFE was essentially alitude hold.