slash in filenames also for Create_file_log_event.


client/mysqlbinlog.cc:
  BUG#34355: mysqlbinlog outputs backslash as path separator for 4.1 binlogs
  Problem: When the windows version of mysqlbinlog reads 4.1 binlogs
  containing LOAD DATA INFILE, it outputs backslashes as path separators in
  filenames. However, the output is typically piped to a client, and client
  expects forward slashes.
  Fix: Replace '\\' by '/' in filenames.