perf python scripting: Add futex-contention script

perf python scripting: Add futex-contention script

The equivalent to this SystemTAP script:

http://sourceware.org/systemtap/wiki/WSFutexContention

[root@doppio ~]# perf trace futex-contention
Press control+C to stop and show the summary
^Cnpviewer.bin[15242] lock 7f0a8be19104 contended 29 times, 72806 avg ns
npviewer.bin[15242] lock 7f0a8be19130 contended 2 times, 1355 avg ns
synergyc[17245] lock f127f4 contended 1 times, 1830569 avg ns
firefox[15116] lock 7f2b7238af0c contended 168 times, 1230390 avg ns
synergyc[17245] lock f2fc20 contended 1 times, 33149 avg ns
npviewer.bin[15255] lock 7f0a8be19074 contended 155 times, 73047 avg ns
npviewer.bin[15255] lock 7f0a8be190a0 contended 127 times, 7088 avg ns
synergyc[17247] lock f12854 contended 1 times, 46741 avg ns
synergyc[17245] lock f12610 contended 1 times, 7358 avg ns
[root@doppio ~]#

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>