BUG#19459 (BINLOG RBR command does not lock tables correctly causing

crash for, e.g., NDB):

Before, mysqlbinlog printed table map events as a separate statement, so
when executing the event, the opened table was subsequently closed
when the statement ended. Instead, the row-based events that make up
a statement are now printed as *one* BINLOG statement, which means
that the table maps and the following *_rows_log_event events are
executed fully before the statement ends.

Changing implementation of BINLOG statement to be able to read the 
emitted format, which now consists of several chunks of BASE64-encoded
data.


client/mysqlbinlog.cc:
  Using IO_CACHE to print events instead of directly to file.
  Factoring out code to write event header and base64 representation into
  separate function.
mysys/mf_iocache2.c:
  Correcting name in documentation.
sql/log_event.cc:
  Adding class Write_on_release_cache that holds an IO_CACHE and that
  will write contents of IO_CACHE to a designated file on destruction.
  
  Changing signature of event printing functions print_header() and print_base64()
  to write to IO_CACHE and changing *all* calls in those functions in accordance.
  This means that all printing functions now print to an IO_CACHE instead of to a file,
  and that the IO_CACHE is then copied to the file.
  
  The print() function have the same signature as before, but since it is
  using print_header() and print_base64(), the data will now be printed
  to an IO_CACHE and then copied to the file.
  
  Changing row-based replication events to incrementally build one
  BINLOG statement for all events making up a statement.
sql/log_event.h:
  Changing signature of event printing functions print_header() and
  print_base64() to write to an IO_CACHE instead of a file.
  
  Changing row-based replication events to incrementally build one
  BINLOG statement for all events making up a statement.
  
  Adding a head_cache and a body_cache to cache statement comment 
  and statement body respectively. In addition, the head_cache is used
  when printing other events than the RBR events.
sql/sql_binlog.cc:
  Changing code to be able to decode several pieces of base64-encoded data
  for a BINLOG statement. The BINLOG statement now consists of several pieces
  of BASE64-encoded data, so once a block has been decoded and executed, the
  next block has to be read from the statement until there is no more
  data to read.

mysys/mf_iocache2.c

@@ -28,7 +28,7 @@
   Copy contents of an IO_CACHE to a file.
 
   SYNOPSIS
-    copy_io_cache_to_file()
+    my_b_copy_to_file()
     cache  IO_CACHE to copy from
     file   File to copy to