vl_dsift.c: fixes error messages.
vl_dsift.c: fixes error messages.

WangDequan/vlfeat,WangDequan/vlfeat,hongzhili/vlfeat,mylxiaoyi/vlfeat,rxl194/vlfeat,richarddzh/vlfeat,richarddzh/vlfeat,rxl194/vlfeat,mylxiaoyi/vlfeat,CansenJIANG/vlfeat,WangDequan/vlfeat,erexhepa/vlfeat,CansenJIANG/vlfeat,CansenJIANG/vlfeat,vlfeat/vlfeat,richarddzh/vlfeat,qubick/vlfeat,erexhepa/vlfeat,rxl194/vlfeat,erexhepa/vlfeat,j-bo/vlfeat,j-bo/vlfeat,mylxiaoyi/vlfeat,mylxiaoyi/vlfeat,hongzhili/vlfeat,qubick/vlfeat,j-bo/vlfeat,erexhepa/vlfeat,qubick/vlfeat,CansenJIANG/vlfeat,cvfish/vlfeat,qubick/vlfeat,rxl194/vlfeat,cvfish/vlfeat,cvfish/vlfeat,vlfeat/vlfeat,cvfish/vlfeat,vlfeat/vlfeat,hongzhili/vlfeat,mylxiaoyi/vlfeat,richarddzh/vlfeat,richarddzh/vlfeat,CansenJIANG/vlfeat,qubick/vlfeat,hongzhili/vlfeat,vlfeat/vlfeat,erexhepa/vlfeat,rxl194/vlfeat,WangDequan/vlfeat,j-bo/vlfeat,CansenJIANG/vlfeat,hongzhili/vlfeat,WangDequan/vlfeat,WangDequan/vlfeat,richarddzh/vlfeat,vlfeat/vlfeat,j-bo/vlfeat,vlfeat/vlfeat,cvfish/vlfeat,mylxiaoyi/vlfeat,erexhepa/vlfeat,cvfish/vlfeat,rxl194/vlfeat,hongzhili/vlfeat,qubick/vlfeat