Make giface.cpp compile when DSSI support is disabled.
Make giface.cpp compile when DSSI support is disabled.

Signed-off-by: David Täht <3c363836cf4e16666669a25da280a1865c2d2874@teklibre.com>

jnetterf/calf,jnetterf/calf,jnetterf/calf,jnetterf/calf,jnetterf/calf,adiknoth/calf,zamaudio/calf-LR4,zamaudio/calf-LR4,adiknoth/calf,zamaudio/calf-LR4,adiknoth/calf,adiknoth/calf,adiknoth/calf,zamaudio/calf-LR4,zamaudio/calf-LR4