lbp.c: fix a bug requiring the output buffer to be cleared
lbp.c: fix a bug requiring the output buffer to be cleared

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