library: a tweak to the UNREF_RPTHASH code, <pids> api

If a hash results report is output (via UNREF_RPTHASH)
a portion is devoted to occupied table entries ordered
by depth. There is a possibility that some depths will
not be found among existing occupied table entries and
to avoid any confusion probably should not be printed.

[ to illustrate the potential for confusion prior to ]
[ this patch, force a very small table size (like 8) ]
[ & then trigger the procps_pids_unref() eoj report. ]

So this patch ensures only 'in use' entries are shown.

[ admittedly, all of the remaining logic in the loop ]
[ could/should be subordinate to this new 'if' test, ]
[ but we will keep the change to a minimum. besides, ]
[ there's no harm subtracting/adding a zero numdepth ]
[ especially since the chance of a zero is very low. ]

Signed-off-by: Jim Warner <james.warner@comcast.net>

proc/pids.c

@@ -727,7 +727,7 @@ static void pids_unref_rpthash (
         for (pop = total_occupied, cross_foot = 0; maxdepth; maxdepth--) {
             for (i = 0, numdepth = 0; i < HHASH_SIZE; i++)
                 if (depths[i] == maxdepth) ++numdepth;
-            fprintf(stderr,
+            if (numdepth) fprintf(stderr,
                 "\t %5d (%3d%%) hash table entries at depth %d\n"
                 , numdepth, (numdepth * 100) / total_occupied, maxdepth);
             pop -= numdepth;