Fixed constructor when VLFeat is not set up.
Fixed constructor when VLFeat is not set up.

andersbll/vlbenchmarks,andersbll/vlbenchmarks,andersbll/vlbenchmarks,vlfeat/vlbenchmarks,CVML/vlbenchmarks,CVML/vlbenchmarks,andersbll/vlbenchmarks,vlfeat/vlbenchmarks,vlfeat/vlbenchmarks,CVML/vlbenchmarks