Fix warnings: comparison between signed and unsigned integer expressions
Fix warnings: comparison between signed and unsigned integer expressions

DaikiMaekawa/pcl,kanster/pcl,lebronzhang/pcl,cascheberg/pcl,drmateo/pcl,wgapl/pcl,ipa-rmb/pcl,mikhail-matrosov/pcl,shyamalschandra/pcl,shyamalschandra/pcl,cascheberg/pcl,cascheberg/pcl,stfuchs/pcl,mikhail-matrosov/pcl,stefanbuettner/pcl,chenxingzhe/pcl,shyamalschandra/pcl,drmateo/pcl,lebronzhang/pcl,raydtang/pcl,Tabjones/pcl,krips89/pcl_newfeatures,cascheberg/pcl,shyamalschandra/pcl,shangwuhencc/pcl,stefanbuettner/pcl,nikste/pcl,Tabjones/pcl,nikste/pcl,DaikiMaekawa/pcl,stfuchs/pcl,lebronzhang/pcl,ipa-rmb/pcl,chenxingzhe/pcl,raydtang/pcl,ipa-rmb/pcl,DaikiMaekawa/pcl,DaikiMaekawa/pcl,KevenRing/vlp,mikhail-matrosov/pcl,MMiknis/pcl,stefanbuettner/pcl,nikste/pcl,lebronzhang/pcl,krips89/pcl_newfeatures,MMiknis/pcl,KevenRing/pcl,nikste/pcl,KevenRing/pcl,shangwuhencc/pcl,MMiknis/pcl,stefanbuettner/pcl,damienjadeduff/pcl,drmateo/pcl,KevenRing/vlp,chenxingzhe/pcl,lebronzhang/pcl,krips89/pcl_newfeatures,DaikiMaekawa/pcl,wgapl/pcl,stefanbuettner/pcl,kanster/pcl,raydtang/pcl,krips89/pcl_newfeatures,Tabjones/pcl,damienjadeduff/pcl,drmateo/pcl,raydtang/pcl,kanster/pcl,KevenRing/vlp,cascheberg/pcl,shyamalschandra/pcl,krips89/pcl_newfeatures,damienjadeduff/pcl,kanster/pcl,Tabjones/pcl,stfuchs/pcl,chenxingzhe/pcl,mikhail-matrosov/pcl,KevenRing/pcl,Tabjones/pcl,stfuchs/pcl,MMiknis/pcl,ipa-rmb/pcl,wgapl/pcl,KevenRing/pcl,chenxingzhe/pcl,kanster/pcl,nikste/pcl,KevenRing/pcl,KevenRing/vlp,KevenRing/vlp,drmateo/pcl,MMiknis/pcl,wgapl/pcl,shangwuhencc/pcl,damienjadeduff/pcl,ipa-rmb/pcl,wgapl/pcl,stfuchs/pcl,shangwuhencc/pcl,damienjadeduff/pcl,shangwuhencc/pcl,mikhail-matrosov/pcl,raydtang/pcl