Fix DEBUG LOADAOF so that redis-server will not crash unexpectedly and will not be inconsistent after we call debug loadaof. Before this commit, there were 2 problems:
Fix DEBUG LOADAOF so that redis-server will not crash unexpectedly
and will not be inconsistent after we call debug loadaof.
Before this commit, there were 2 problems:

1, When appendonly is set to no and there is not a appendonly file,
   redis-server will crash if we call DEBUG LOADAOF.
2, When appendonly is set to no and there is a appendonly file,
   redis-server will hold different data after loading  appendonly
   file.

JackieXie168/redis,JackieXie168/redis,JackieXie168/redis,JackieXie168/redis