Make Basis Universal import quiet unless engine is in verbose mode

[Calinou]

This makes Basis Universal stdout match other compression modes.

Previously, this was printed on every Basis Universal import:

Total basis file slices: 1
Slice: 0, alpha: 1, orig width/height: 96x16384, width/height: 96x16384, first_block: 0, image_index: 0, mip_level: 0, iframe: 0

[akien-mga]

Thanks!