Add taskstats reporting tool

Add a tool for querying and printing out the kernel's taskstats
structure. This structure contains various profiling information about a
given process or thread group.

Sample output:

    Basic task statistics
    ---------------------
    Stats version:           8
    Exit code:               0
    Flags:                   0x2
    Nice value:              0
    Command name:            init
    Scheduling discipline:   0
    UID:                     0
    GID:                     0
    PID:                     1
    PPID:                    0
    Begin time:              Fri Sep 20 17:06:14 2013
    Elapsed time:            611384577 usec
    User CPU time:           980000 usec
    Minor page faults:       515
    Major page faults:       0
    Scaled user time:        980000 usec
    Scaled system time:      2590000 usec

    Delay accounting
    ----------------
                     Count     Delay (ms)  Average delay     Real delay    Scaled real  Virtual delay
    CPU               1101         90.615          0.082       3570.000       3570.000       3620.204
    IO                  45         50.155          1.115
    Swap                 0          0.000          0.000
    Reclaim              0          0.000          0.000

    Extended accounting fields
    --------------------------
    Average RSS usage:       0.348 MB
    Average VM usage:        0.727 MB
    RSS high water mark:     548 KB
    VM high water mark:      688 KB
    IO bytes read:           330752
    IO bytes written:        979968
    IO read syscalls:        17408
    IO write syscalls:       0

    Per-task/thread statistics
    --------------------------
    Voluntary switches:      768
    Involuntary switches:    333

Change-Id: I4dab68d98de5db0f9112bec014872a067684f799
4 files changed