tools lib traceevent: Implement new API tep_get_ref()

This patch implements a new API of the tracevent library:

  int tep_get_ref(struct tep_handle *tep);

The API returns the reference counter "ref_count" of the tep handler.
As "struct tep_handle" is internal only, its members cannot be accessed
by the library users, the API is used to get the reference counter.
Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20181130154646.890615385@goodmis.orgSigned-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/event-parse.c

@@ -6730,6 +6730,13 @@ void tep_ref(struct tep_handle *pevent)
 	pevent->ref_count++;
 }
 
+int tep_get_ref(struct tep_handle *tep)
+{
+	if (tep)
+		return tep->ref_count;
+	return 0;
+}
+
 void tep_free_format_field(struct tep_format_field *field)
 {
 	free(field->type);

tools/lib/traceevent/event-parse.h

@@ -581,6 +581,7 @@ struct tep_handle *tep_alloc(void);
 void tep_free(struct tep_handle *pevent);
 void tep_ref(struct tep_handle *pevent);
 void tep_unref(struct tep_handle *pevent);
+int tep_get_ref(struct tep_handle *tep);
 
 /* access to the internal parser */
 void tep_buffer_init(const char *buf, unsigned long long size);