covdet.c: minor cosmetic fixes
covdet.c: minor cosmetic fixes

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