FLUSH STATUS doesn't clear the values of the global status variables.
The test case is reduced to testing session local Com-variables until
FLUSH GLOBAL STATUS is implemented.


mysql-test/r/status.result:
  Reduce test to testing session status until 'FLUSH GLOBAL STATUS' is
  implemented.
mysql-test/t/disabled.def:
  Enable main.status.test.
mysql-test/t/status.test:
  Reduce test to testing session status until 'FLUSH GLOBAL STATUS' is
  implemented.