preface.h in rgeo-2.4.0

- old
+ new

@@ -25,9 +25,14 @@
 #define RGEO_GEOS_SUPPORTS_ISCCW
 #endif
 #ifdef HAVE_RB_MEMHASH
 #define RGEO_SUPPORTS_NEW_HASHING
 #endif
+#ifdef HAVE_RB_GC_MARK_MOVABLE
+#define mark rb_gc_mark_movable
+#else
+#define mark rb_gc_mark
+#endif
 
 #ifndef RGEO_SUPPORTS_NEW_HASHING
 #define st_index_t int
 #define rb_memhash(x,y) rgeo_internal_memhash(x,y)
 #define rb_hash_start(x) ((st_index_t)(x ^ 0xdeadbeef))