include/rb_gsl.h in gsl-1.12.109 vs include/rb_gsl.h in gsl-1.14.5

@@ -146,6 +146,13 @@
 #include "alf/alf.h"
 #endif
 void Init_alf(VALUE module);
 void Init_geometry(VALUE module);
 
+#ifdef GSL_1_14_LATER
+#include <gsl/gsl_multiset.h>
+extern VALUE cMultiset;
+void Init_multiset(VALUE module);
+
+#endif
+
 #endif