Fix rdb.c dictionary iterator release.
Fix rdb.c dictionary iterator release.

Some times it was not released on error, sometimes it was released two
times because the error path expected the "di" var to be NULL if the
iterator was already released. Thanks to @oranagra for pinging me about
potential problems of this kind inside rdb.c.

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