Use correct header for EXIT_SUCCESS

test/backtrace.cpp

@@ -1,12 +1,13 @@
-#include "../backtrace.hpp"
-#include <iostream>
-
-using namespace std;
-
-
-int
-main (int, char **) {
-    cout << debug::backtrace() << endl;
-
-    return EXIT_SUCCESS;
-}
+#include "../backtrace.hpp"
+#include <iostream>
+#include <cstdlib>
+
+using namespace std;
+
+
+int
+main (int, char **) {
+    cout << debug::backtrace() << endl;
+
+    return EXIT_SUCCESS;
+}