perf tests: Move test__open_syscall_event into separate object

Separating test__open_syscall_event test from the builtin-test into
open-syscall object.

Adding util object under tests directory to gather help functions common
to more tests.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1352508412-16914-3-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/tests/util.c b/tools/perf/tests/util.c
new file mode 100644
index 0000000..748f2e8
--- /dev/null
+++ b/tools/perf/tests/util.c
@@ -0,0 +1,30 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include "tests.h"
+#include "debugfs.h"
+
+int trace_event__id(const char *evname)
+{
+	char *filename;
+	int err = -1, fd;
+
+	if (asprintf(&filename,
+		     "%s/syscalls/%s/id",
+		     tracing_events_path, evname) < 0)
+		return -1;
+
+	fd = open(filename, O_RDONLY);
+	if (fd >= 0) {
+		char id[16];
+		if (read(fd, id, sizeof(id)) > 0)
+			err = atoi(id);
+		close(fd);
+	}
+
+	free(filename);
+	return err;
+}