hog.c: fix a bug in the bilinear interpolated variant of the descriptor
hog.c: fix a bug in the bilinear interpolated variant of the descriptor

Fortunately this variant is seldom used in practice.

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