perf tools: Move 'struct perf_sample' to a separate header file to disentangle headers

Some places were including event.h just to get 'struct perf_sample',
move it to a separate place so that we speed up a bit the build.

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

tools/perf/util/trace-event-scripting.c

diff --git a/tools/perf/util/trace-event-scripting.c b/tools/perf/util/trace-event-scripting.c
index 7172ca0..636a010 100644
--- a/tools/perf/util/trace-event-scripting.c
+++ b/tools/perf/util/trace-event-scripting.c
@@ -12,9 +12,9 @@
 
 #include "debug.h"
 #include "trace-event.h"
-#include "event.h"
 #include "evsel.h"
 #include <linux/zalloc.h>
+#include "util/sample.h"
 
 struct scripting_context *scripting_context;