perf: Add the timechart tool

timechart is a tool to visualize what is going on in the system.

The user makes a trace of what is going on with

 > perf record --timechart /usr/bin/some_command

and then can turn the output of this into an svg file

 > perf timechart

which then can be viewed with any SVG view; inkscape works well
enough for me.

The idea behind timechart is to create a "infinitely zoomable"
picture; something that has high level information on a 1:1 zoom
level, but which exposes more details every time you zoom into a
specific area.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20090912130713.6a77bbc0@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>