client/mysqltest.c:
  Extend 'do_block' to be able to process a !<expression>. 
  Making it possible to do 'if(!$i)' and 'while(!$i)'
mysql-test/r/mysqltest.result:
  Update test results
mysql-test/t/mysqltest.test:
  Add test for if
  Add test for while with ! expr