perf tools: Pass tool context in the the perf_event_ops functions

So that we don't need to have that many globals.

Next steps will remove the 'session' pointer, that in most cases is
not needed.

Then we can rename perf_event_ops to 'perf_tool' that better describes
this class hierarchy.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-wp4djox7x6w1i2bab1pt4xxp@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/build-id.c

@@ -13,8 +13,10 @@
 #include "symbol.h"
 #include <linux/kernel.h>
 #include "debug.h"
+#include "session.h"
 
-static int build_id__mark_dso_hit(union perf_event *event,
+static int build_id__mark_dso_hit(struct perf_event_ops *ops __used,
+				  union perf_event *event,
 				  struct perf_sample *sample __used,
 				  struct perf_evsel *evsel __used,
 				  struct perf_session *session)
@@ -38,7 +40,8 @@ static int build_id__mark_dso_hit(union perf_event *event,
 	return 0;
 }
 
-static int perf_event__exit_del_thread(union perf_event *event,
+static int perf_event__exit_del_thread(struct perf_event_ops *ops __used,
+				       union perf_event *event,
 				       struct perf_sample *sample __used,
 				       struct perf_session *session)
 {