Fix objectSetLRUOrLFU() when LFU underflows.
Fix objectSetLRUOrLFU() when LFU underflows.

soveran/redis,neomantra/redis,soloestoy/redis,oranagra/redis,PKRoma/redis,charsyam/redis,yossigo/redis,oranagra/redis,neomantra/redis,pmem/redis,soloestoy/redis,ofirluzon/redis,yossigo/redis,neomantra/redis,oranagra/redis,soloestoy/redis,soloestoy/redis,yossigo/redis,ofirluzon/redis,oranagra/redis,PKRoma/redis,neomantra/redis,oranagra/redis,yossigo/redis,yossigo/redis,soloestoy/redis,ctripcorp/redis,pmem/redis,soveran/redis,soveran/redis,PKRoma/redis,charsyam/redis,antirez/redis,ofirluzon/redis,soveran/redis,pmem/redis,charsyam/redis,ofirluzon/redis,neomantra/redis,ctripcorp/redis,antirez/redis,PKRoma/redis,charsyam/redis,antirez/redis,antirez/redis,charsyam/redis,pmem/redis,ctripcorp/redis,PKRoma/redis,ctripcorp/redis,ofirluzon/redis