perf tools: Add a function to calculate sample event size

Add perf_event__sample_event_size() which can be used when synthesizing
sample events to determine how big the resulting event will be, and
therefore how much memory to allocate.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1377591794-30553-11-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 1c80e13..93130d8 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -229,6 +229,8 @@
 
 const char *perf_event__name(unsigned int id);
 
+size_t perf_event__sample_event_size(const struct perf_sample *sample, u64 type,
+				     u64 sample_regs_user, u64 read_format);
 int perf_event__synthesize_sample(union perf_event *event, u64 type,
 				  u64 sample_regs_user, u64 read_format,
 				  const struct perf_sample *sample,