Remove default GC tweak
Remove default GC tweak

This reverts the GC behavior to the Go default of triggering GC when the
heap has grown 100% compared to after the previous GC. We were setting
this to 25% to keep memory usage at a minimum, but it has a pretty
severe performance cost (especially when syncing large files) as we keep
triggering GC too often.

This documents the tweak in the `-help` message so users can decide for
themselves, and sticks to whatever the Go runtime developers thinks is
best for the default.

ProactiveServices/syncthing,butlife/syncthing,lkwg82/syncthing,TheBigBear/syncthing,kc1212/syncthing,itscaro/syncthing,guerrerocarlos/syncthing,xduugu/syncthing,wsgcsysadmin/syncthing,kc1212/syncthing,xduugu/syncthing,Zillode/syncthing,pembo210/syncthing,pembo210/syncthing,printedheart/syncthing,imsodin/syncthing,letiemble/syncthing,syncthing/syncthing,kamadak/syncthing,le9i0nx/syncthing,mateon1/syncthing,brgmnn/syncthing,buinsky/syncthing,jryans/syncthing,josephyzhou/syncthing,rumpelsepp/syncthing,roth1002/syncthing,jemmy655/syncthing,uok/syncthing,abhishekgahlot/syncthing,Kudalufi/syncthing,MinFu/syncthing,letiemble/syncthing,kozec/syncthing,tenebreux/syncthing,mateon1/syncthing,canton7/syncthing,plouj/syncthing,pembo210/syncthing,ProactiveServices/syncthing,ProactiveServices/syncthing,manveru/syncthing,syncthing/syncthing,flyzjhz/syncthing,Kudalufi/syncthing,TheBigBear/syncthing,makeTaller/syncthing,danieldc/syncthing,tenebreux/syncthing,buinsky/syncthing,Zillode/syncthing,makeTaller/syncthing,nrm21/syncthing,uok/syncthing,nrm21/syncthing,le9i0nx/syncthing,manveru/syncthing,plouj/syncthing,michalliu/whale,MinFu/syncthing,makeTaller/syncthing,wsgcsysadmin/syncthing,manveru/syncthing,mcanthony/syncthing,beni55/syncthing,beni55/syncthing,jgke/syncthing,michalliu/whale,rumpelsepp/syncthing,mcanthony/syncthing,jbfavre/syncthing,AudriusButkevicius/syncthing,jryans/syncthing,cherylquirion/syncthing,indradhanush/syncthing,wweich/syncthing,butlife/syncthing,ProactiveServices/syncthing,ZdenekBrichacek/syncthing,kralo/syncthing,Kudalufi/syncthing,mateon1/syncthing,flyzjhz/syncthing,jryans/syncthing,guerrerocarlos/syncthing,syncthing/syncthing,michalliu/whale,gillisig/syncthing,jbfavre/syncthing,modulexcite/syncthing,gillisig/syncthing,uok/syncthing,kattunga/syncthing,indradhanush/syncthing,burkemw3/syncthing,danieldc/syncthing,wsgcsysadmin/syncthing,toddleish/syncthing,abhishekgahlot/syncthing,atyenoria/syncthing,trojanspike/syncthing,kluppy/syncthing,nrm21/syncthing,toddleish/syncthing,letiemble/syncthing,imsodin/syncthing,buinsky/syncthing,jemmy655/syncthing,kozec/syncthing,kluppy/syncthing,kattunga/syncthing,wweich/syncthing,norgeous/syncthing,danieldc/syncthing,krig/syncthing,syncthing/syncthing,trojanspike/syncthing,MinFu/syncthing,kattunga/syncthing,jgke/syncthing,pembo210/syncthing,alex2108/syncthing,TheBigBear/syncthing,brgmnn/syncthing,bigscoop/syncthing,mateon1/syncthing,kozec/syncthing,kc1212/syncthing,beni55/syncthing,wsgcsysadmin/syncthing,burkemw3/syncthing,trojanspike/syncthing,itscaro/syncthing,AudriusButkevicius/syncthing,toddleish/syncthing,Kudalufi/syncthing,lkwg82/syncthing,rumpelsepp/syncthing,AudriusButkevicius/syncthing,plouj/syncthing,kralo/syncthing,abhishekgahlot/syncthing,TheBigBear/syncthing,brgmnn/syncthing,ralder/syncthing,indradhanush/syncthing,norgeous/syncthing,canton7/syncthing,lkwg82/syncthing,jgke/syncthing,norgeous/syncthing,butlife/syncthing,gillisig/syncthing,lkwg82/syncthing,jemmy655/syncthing,cherylquirion/syncthing,gillisig/syncthing,uok/syncthing,roth1002/syncthing,tenebreux/syncthing,plouj/syncthing,jbfavre/syncthing,makeTaller/syncthing,imsodin/syncthing,butlife/syncthing,manveru/syncthing,alex2108/syncthing,toddleish/syncthing,ralder/syncthing,josephyzhou/syncthing,modulexcite/syncthing,modulexcite/syncthing,brgmnn/syncthing,cherylquirion/syncthing,mcanthony/syncthing,kattunga/syncthing,guerrerocarlos/syncthing,ZdenekBrichacek/syncthing,letiemble/syncthing,bigscoop/syncthing,trojanspike/syncthing,atyenoria/syncthing,jgke/syncthing,flyzjhz/syncthing,itscaro/syncthing,arkhi/syncthing,le9i0nx/syncthing,jbfavre/syncthing,xduugu/syncthing,printedheart/syncthing,kluppy/syncthing,kralo/syncthing,itscaro/syncthing,buinsky/syncthing,kluppy/syncthing,kamadak/syncthing,ZdenekBrichacek/syncthing,cherylquirion/syncthing,canton7/syncthing,burkemw3/syncthing,burkemw3/syncthing,indradhanush/syncthing,kamadak/syncthing,imsodin/syncthing,rumpelsepp/syncthing,josephyzhou/syncthing,syncthing/syncthing,Zillode/syncthing,imsodin/syncthing,ralder/syncthing,krig/syncthing,ralder/syncthing,nrm21/syncthing,atyenoria/syncthing,kc1212/syncthing,flyzjhz/syncthing,modulexcite/syncthing,arkhi/syncthing,guerrerocarlos/syncthing,MinFu/syncthing,michalliu/whale,printedheart/syncthing,ZdenekBrichacek/syncthing,kozec/syncthing,AudriusButkevicius/syncthing,wweich/syncthing,kralo/syncthing,bigscoop/syncthing,atyenoria/syncthing,xduugu/syncthing,alex2108/syncthing,canton7/syncthing,abhishekgahlot/syncthing,Zillode/syncthing,josephyzhou/syncthing,roth1002/syncthing,alex2108/syncthing,wweich/syncthing,tenebreux/syncthing,le9i0nx/syncthing,arkhi/syncthing,mcanthony/syncthing,norgeous/syncthing,jryans/syncthing,kamadak/syncthing,roth1002/syncthing,jemmy655/syncthing,syncthing/syncthing,arkhi/syncthing,danieldc/syncthing,bigscoop/syncthing,printedheart/syncthing,beni55/syncthing,krig/syncthing,krig/syncthing