Streams: RDB loading. RDB saving modified.
Streams: RDB loading. RDB saving modified.

After a few attempts it looked quite saner to just add the last item ID
at the end of the serialized listpacks, instead of scanning the last
listpack loaded from head to tail just to fetch it. It's a disk space VS
CPU-and-simplicity tradeoff basically.

neomantra/redis,yossigo/redis,rogerchina/redis,Sciumo/redis,antirez/redis,spinlock/redis,GitHubMota/redis,pmem/redis,charsyam/redis,rogerchina/redis,ofirluzon/redis,soloestoy/redis,ofirluzon/redis,soloestoy/redis,charsyam/redis,charsyam/redis,neomantra/redis,PKRoma/redis,yossigo/redis,yossigo/redis,spinlock/redis,spinlock/redis,GitHubMota/redis,neomantra/redis,pmem/redis,nnog/redis,spinlock/redis,Sciumo/redis,Sciumo/redis,antirez/redis,antirez/redis,PKRoma/redis,soloestoy/redis,GitHubMota/redis,ofirluzon/redis,PKRoma/redis,pmem/redis,oranagra/redis,charsyam/redis,yossigo/redis,neomantra/redis,soveran/redis,neomantra/redis,oranagra/redis,soloestoy/redis,nnog/redis,charsyam/redis,oranagra/redis,Sciumo/redis,oranagra/redis,yossigo/redis,soveran/redis,ofirluzon/redis,pmem/redis,ctripcorp/redis,ofirluzon/redis,rogerchina/redis,soloestoy/redis,PKRoma/redis,nnog/redis,soveran/redis,rogerchina/redis,GitHubMota/redis,antirez/redis,ctripcorp/redis,ctripcorp/redis,oranagra/redis,nnog/redis,ctripcorp/redis,PKRoma/redis,soveran/redis