A BINARY field is represented by the Field_string class. The space character
is used as the filler for unused characters in such a field. But a BINARY field 
should use \x00 instead.

Field_string:reset() now detects whether the current field is a BINARY one
and if so uses the \x00 character as a default value filler.


sql/field.h:
  Bug#14171: Wrong internal default value for a BINARY field.
  Field_string:reset() now detects whether the current field is a BINARY one
  and if so uses the \x00 character as a default value filler.
mysql-test/r/type_binary.result:
  Added a test case for the bug#14171: Wrong internal default value for a BINARY field.
mysql-test/t/type_binary.test:
  Added a test case for the bug#14171: Wrong internal default value for a BINARY field.