iproute2 / tbf with large burst seems broken again

[Denys Fedoryschenko <denys@visp.net.lb>]

Found issue, it seems tc_core_time2tick will overflow with increased 
resolution on large bucket values. But no idea how to fix it :-(

I add a warning, something like
 unsigned tc_core_time2tick(unsigned time)
 {
+       long long temp = time*tick_in_usec;
+       if (temp > INT_MAX)
+           printf("tc_core_time2tick() overflow!\n");
        return time*tick_in_usec;
 }

Maybe it is good to add in iproute2 mainstream, so user will be warned if 
buffer set too large? (and it will not set incorrect values, that lead to 
unpredictable results.