mysql-next-mr-bugfixing.

Bug no 32858 was fixed in two different ways in what was
then called mysql 5.1 and 6.0. The fix in 6.0 was very
different since bugfix no 33204 was present.  Furthermore,
the two fixes were not compatible. Hence in order to
backport Bug#33204 to the 5.1-based mysql-next-mr-bugfixing,
it was necessary to remove the 5.1 fix of 32858 and apply
the 6.0 version of the fix.


mysql-test/r/subselect.result:
  Bug#33204-backport: Test result
mysql-test/r/union.result:
  
  Bug#33204-backport:
  - Reversal of test result: bugfix no 32858 for 5.1
  - Application of test result: bugfix no 32858 for 6.0
mysql-test/t/subselect.test:
  Bug#33204-backport: 
  - Changed tests
  - Test case
mysql-test/t/union.test:
  Bug#33204-backport:
  - Reversal of test: bugfix no 32858 for 5.1
  - Application of test: bugfix no 32858 for 6.0
sql/sql_class.cc:
  Bug#33204-backport: Reversal of bugfix no 32858 for 5.1
sql/sql_class.h:
  Bug#33204-backport: Reversal of bugfix no 32858 for 5.1
sql/sql_yacc.yy:
  Bug#33204-backport:
  - Reversal of bugfix no 32858 for 5.1
  - Application of bugfix no 32858 for 6.0
  - Application of bugfix no 33204