The slave was not able to find the correct row in the innodb
table, because the row fetched from the innodb table would not
match the before image. This happened because the (don't care)
bytes in the NULLed fields would change once the row was stored
in the storage engine (from zero to the default value). This
would make bulk memory comparison (using memcmp) to fail.
  
We fix this by taking a preventing measure and avoiding memcmp
for tables that contain nullable fields. Therefore, we protect
the slave search routine from engines that return arbitrary
values for don't care bytes (in the nulled fields). Instead, the
slave thread will only check null_bits and those fields that are
not set to NULL when comparing the before image against the
storage engine row.

mysql-test/extra/rpl_tests/rpl_record_compare.test:
  Added test case to the include file so that this is tested 
  with more than one engine.
mysql-test/suite/rpl/r/rpl_row_rec_comp_innodb.result:
  Result update.
mysql-test/suite/rpl/r/rpl_row_rec_comp_myisam.result:
  Result update.
mysql-test/suite/rpl/t/rpl_row_rec_comp_myisam.test:
  Moved the include file last, so that the result from
  BUG#11766865 is not intermixed with the result for
  BUG#11760454.
sql/log_event.cc:
  Skips memory comparison if the table has nullable 
  columns and compares only non-nulled fields in the
  field comparison loop.