Address a "ps" command performance degradation that was introduced by
a crash-7.0.4 patch which added per-thread task_struct.rss_stat page
counts to the task's mm_struct.rss_stat page counts in order to show
an accurate/synchronized RSS value.  Without the patch, the "ps"
command performance would degrade as the number of tasks increased,
most notably when there were thousands of tasks.
(panfy.fnst@cn.fujitsu.com, anderson@redhat.com)