[PATCH] speed up /proc/pid/stat, statm

[KAMEZAWA Hiroyuki]

This patch is based onto linux-mm
procfs-add-num_to_str-to-speed-up-proc-stat.patch +
procfs-add-num_to_str-to-speed-up-proc-stat-fix.patch

This patch is for /proc/pid/stat and you can see the effect with realisitc applications.