The wrong value was being reported as the field_length for BIT
  fields, resulting in confusion for at least Connector/J. The
  field_length is now always the number of bits in the field, as
  it should be.


mysql-test/r/type_bit.result:
  Add new results
mysql-test/r/type_bit_innodb.result:
  Add new results
mysql-test/t/type_bit.test:
  Add new regression test
mysql-test/t/type_bit_innodb.test:
  Add new regression test
sql/field.cc:
  Fix Field_bit->field_length to actually report the display width, and
  store the bytes stored in the rec in the new bytes_in_rec member.
sql/field.h:
  Fix Field_bit::field_length to store the correct value, adding
  Field_bit::bytes_in_rec to remember the number of bytes used for
  storing the value. Remove Field_bit_as_char::create_length, as it
  is now redundant.
sql/ha_ndbcluster.cc:
  Handle field_length of Field_bit actually being the display width (# of bits).
sql/key.cc:
  Fix inappropriate use of field->field_length for BIT field.