Fix rand_r header

Author: jimun_lee

PWGLF/Tasks/Resonances/kstarInJets.cxx

@@ -47,13 +47,13 @@
 #include <cmath>
 #include <cstddef>
 #include <cstdlib>
-#include <stdlib.h>
 #include <memory>
-
 #include <string>
 #include <utility>
 #include <vector>
 
+#include <stdlib.h>
+
 using namespace o2;
 using namespace o2::framework;
 using namespace o2::framework::expressions;