Replication using replicate-rewrite-db did not work for LOAD DATA INFILE.
Now is does. There was one place in the code that used current database
instead of the rewrite database.
as we already have db_len in Log_event. Only if rewrite_db() changed the db we need a strlen
(so we now do the strlen() in rewrite_db). Plus a test (we had none for --replicate-rewrite-db :( ).
