perf annotate: Print a sorted summary of annotated overhead lines

perf annotate: Print a sorted summary of annotated overhead lines

It's can be very annoying to scroll down perf annotated output
until we find relevant overhead.

Using the -l option, you can now have a small summary sorted per
overhead in the beginning of the output.

Example:

./perf annotate -l -k ../../vmlinux -s __lock_acquire

Sorted summary for file ../../vmlinux
----------------------------------------------

   12.04 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:1653
    4.61 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:1740
    3.77 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:1775
    3.56 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:1653
    2.93 /home/fweisbec/linux/linux-2.6-tip/arch/x86/include/asm/irqflags.h:15
    2.83 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:2545
    2.30 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:2594
    2.20 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:2388
    2.20 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:730
    2.09 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:730
    2.09 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:138
    1.88 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:2548
    1.47 /home/fweisbec/linux/linux-2.6-tip/arch/x86/include/asm/irqflags.h:15
    1.36 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:2594
    1.36 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:730
    1.26 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:1654
    1.26 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:1653
    1.15 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:2592
    1.15 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:1740
    1.15 /home/fweisbec/linux/linux-2.6-tip/kernel/lockdep.c:1740

[...]

Only overhead over 0.5% are summarized.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1244844682-12928-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>