perf: Add a SVG helper library file

The timechart tool writes out SVG format output; this patch adds a
set of helper functions to abstract dealing with SVG from the core
timechart code.

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: <20090912130613.677f0516@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>