viewer: make the frame queue a bit bigger.
viewer: make the frame queue a bit bigger.

Mainly for debugging purposes.

AravisProject/aravis,AravisProject/aravis,AnilRamachandran/aravis,AravisProject/aravis,lu-zero/aravis,lu-zero/aravis,AnilRamachandran/aravis,AravisProject/aravis,AnilRamachandran/aravis,AnilRamachandran/aravis,lu-zero/aravis,lu-zero/aravis,AravisProject/aravis,AnilRamachandran/aravis,lu-zero/aravis