Centralize slave replication handshake aborting.
Centralize slave replication handshake aborting.

Now we have a single function to call in any state of the slave
handshake, instead of using different functions for different states
which is error prone. Change performed in the context of issue #2479 but
does not fix it, since should be functionally identical to the past.
Just an attempt to make replication.c simpler to follow.

pedigree/redis,pedigree/redis,pedigree/redis,xuguruogu/redis,4396/redis,xuguruogu/redis,4396/redis,xuguruogu/redis,xuguruogu/redis,4396/redis,janekmi/redis,janekmi/redis,pedigree/redis,4396/redis,janekmi/redis,janekmi/redis