incorrect binary search in remove_status_vars()

On INSTALL SONAME 'ha_tokudb.so' when TokuDB cannot be installed (for example, because transparent hugepages are enabled), MariaDB hangs.

The reason is the remove_status_vars() function that has incorrectly implemented binary search to remove plugin variables from the all-variables list. The code

      for (; b-a > 0; c= (a+b)/2)

      {

        res= show_var_cmp(list, all+c);

        if (res < 0)

          b= c;

        else if (res > 0)

          a= c;

        else

          break;

      }

in my test, a=129, b=130. So, c=129, in comparison I get res > 0, and the loop continues till infinity.