Fixed constant folding through let statements to not remove them.
Fixed constant folding through let statements to
not remove them.

Also fixed some unused folding rules.
kenkuang1213/Halide,rodrigob/Halide,jiawen/Halide,psuriana/Halide,ronen/Halide,damienfir/Halide,aam/Halide,gchauras/Halide,kgnk/Halide,mikeseven/Halide,aam/Halide,dan-tull/Halide,adasworks/Halide,myrtleTree33/Halide,lglucin/Halide,damienfir/Halide,mcanthony/Halide,jiawen/Halide,myrtleTree33/Halide,dougkwan/Halide,mcanthony/Halide,tdenniston/Halide,fengzhyuan/Halide,dan-tull/Halide,delcypher/Halide,mikeseven/Halide,adasworks/Halide,psuriana/Halide,adasworks/Halide,rodrigob/Halide,dan-tull/Halide,kgnk/Halide,kenkuang1213/Halide,dan-tull/Halide,kenkuang1213/Halide,dan-tull/Halide,gchauras/Halide,tdenniston/Halide,delcypher/Halide,adasworks/Halide,adasworks/Halide,gchauras/Halide,kenkuang1213/Halide,kgnk/Halide,rodrigob/Halide,damienfir/Halide,lglucin/Halide,mikeseven/Halide,ayanazmat/Halide,dougkwan/Halide,dougkwan/Halide,adasworks/Halide,aam/Halide,dougkwan/Halide,mikeseven/Halide,dan-tull/Halide,lglucin/Halide,dan-tull/Halide,fengzhyuan/Halide,myrtleTree33/Halide,psuriana/Halide,delcypher/Halide,smxlong/Halide,fengzhyuan/Halide,myrtleTree33/Halide,delcypher/Halide,myrtleTree33/Halide,kenkuang1213/Halide,lglucin/Halide,smxlong/Halide,lglucin/Halide,jiawen/Halide,mcanthony/Halide,dougkwan/Halide,psuriana/Halide,jiawen/Halide,myrtleTree33/Halide,damienfir/Halide,damienfir/Halide,aam/Halide,aam/Halide,ayanazmat/Halide,fengzhyuan/Halide,delcypher/Halide,delcypher/Halide,ayanazmat/Halide,mcanthony/Halide,ronen/Halide,delcypher/Halide,rodrigob/Halide,smxlong/Halide,lglucin/Halide,psuriana/Halide,myrtleTree33/Halide,tdenniston/Halide,tdenniston/Halide,smxlong/Halide,ayanazmat/Halide,dan-tull/Halide,ronen/Halide,ronen/Halide,ayanazmat/Halide,smxlong/Halide,kgnk/Halide,tdenniston/Halide,kenkuang1213/Halide,kgnk/Halide,damienfir/Halide,adasworks/Halide,fengzhyuan/Halide,jiawen/Halide,ronen/Halide,myrtleTree33/Halide,jiawen/Halide,tdenniston/Halide,fengzhyuan/Halide,ronen/Halide,lglucin/Halide,ronen/Halide,fengzhyuan/Halide,damienfir/Halide,ronen/Halide,psuriana/Halide,jiawen/Halide,mcanthony/Halide,kenkuang1213/Halide,damienfir/Halide,fengzhyuan/Halide,gchauras/Halide,gchauras/Halide,gchauras/Halide,delcypher/Halide,mcanthony/Halide,rodrigob/Halide,ayanazmat/Halide,kgnk/Halide,tdenniston/Halide,kenkuang1213/Halide,adasworks/Halide,mikeseven/Halide,smxlong/Halide,aam/Halide,smxlong/Halide,dougkwan/Halide,mcanthony/Halide,smxlong/Halide,kgnk/Halide,mcanthony/Halide,rodrigob/Halide,dougkwan/Halide,rodrigob/Halide,ayanazmat/Halide,aam/Halide,tdenniston/Halide,kgnk/Halide,rodrigob/Halide,dougkwan/Halide,psuriana/Halide,ayanazmat/Halide