perf tests: Add framework for automated perf_event_attr tests

perf tests: Add framework for automated perf_event_attr tests

The idea is run perf session with kidnapping sys_perf_event_open
function. For each sys_perf_event_open call we store the perf_event_attr
data to the file to be checked later against what we expect.

You can run this by:
  $ python ./tests/attr.py -d ./tests/attr/ -p ./perf -v

v2 changes:
  - preserve errno value in the hook

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20121031145247.GB1027@krava.brq.redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>