Port to mariadb-1.0 the following fix from mysql-5.6:

  Revision ID: jorgen.loland@oracle.com-20120314131055-ml54x9deueqfsff4
  BUG#13701206: WHERE A>=B DOES NOT GIVE SAME EXECUTION PLAN
                AS WHERE B<=A (RANGE OPTIMIZER)
 
that fix didn't have a public testcase, so I created one.