covdet.c: some cleanup
covdet.c: some cleanup

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