perf tools: Update documentation info about quipper

The existing link is outdated. The most recent quipper code can be found at the
new URL.

Committer notes:

Quipper is a C++ parser that can be used to convert from a perf.data
file to and from a protobuf, a Chromium OS facility.

Signed-off-by: Simon Que <[e-mail]>
Acked-by: Andi Kleen <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Chong Jiang <[e-mail]>
Link: http://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/Documentation/perf.data-file-format.txt

···
 quipper
 
 The quipper C++ parser is available at
-https://chromium.googlesource.com/chromiumos/platform/chromiumos-wide-profiling/
+https://chromium.googlesource.com/chromiumos/platform2
+
+It is under the chromiumos-wide-profiling/ subdirectory. This library can
+convert a perf data file to a protobuf and vice versa.
+
 Unfortunately this parser tends to be many versions behind and may not be able
 to parse data files generated by recent perf.