perf tools: Fix raw sample reading

Wrong pointer is being passed for raw data sanity checking, when parsing
sample event.

This ends up with invalid event and perf record being stuck in
__perf_session__process_events function during processing build IDs
(process_buildids function).

Following command hangs up in my setup:
	./perf record -e raw_syscalls:sys_enter ls

The fix is to use proper pointer to the raw data instead of the 'u'
union.

Reviewed-by: David Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Neil Horman <nhorman@tuxdriver.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1317308709-9474-2-git-send-email-jolsa@redhat.com


Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>