patch from Gerrit: 07_hostlist__hostrange_pop__hostrange_shift.diff

hostrange_pop()/hostrange_shift(): test for overflow

hostrange_pop():				   
 * retrofitted out_of_memory() test after strdup;
 * tested for negative length/overflow before the while-loop,
   making sure that 'dims' characters also fit in;
 * second snprintf is not tested.

hostrange_shift(): 
 * analogous changes (second snprintf also not tested).