[Bug #19584] Register global variable address before assignment

ruby.c

@@ -641,8 +641,8 @@ ruby_init_loadpath(void)
 #   endif
     rb_obj_hide(selfpath);
     OBJ_FREEZE_RAW(selfpath);
-    rb_libruby_selfpath = selfpath;
     rb_gc_register_address(&rb_libruby_selfpath);
+    rb_libruby_selfpath = selfpath;
 # endif
 #endif