Null pointer dereference in mrb_random_initialize

Sorry I was not quite sure about the scope. This bug is not triggerable in the sandbox, because it does not use the Random class, but it is triggerable in mruby with the following piece of code: ```ruby $r = Random.new a = Object.new def a.to_int $r.rand end $r.initialize a ``` The data pointer of $r is set to NULL before parsing arguments in `mrb_random_init`. The srand() call will try to dereference it to get the mt_state and this results in a crash. The problem lies in `mrbgems/mruby-random/src/random.c` and is similar to #182274: ```c 128 t = (mt_state*)DATA_PTR(self); 129 if (t) { 130 mrb_free(mrb, t); 131 } 132 mrb_data_init(self, NULL, &mt_state_type); 133 134 t = (mt_state *)mrb_malloc(mrb, sizeof(mt_state)); 135 t->mti = N + 1; 136 137 seed = get_opt(mrb); /* Move this up before line 127 */ ``` Please let me know if you are explicitly just looking for bugs affecting the sandbox, so I won't submit invalid reports. Thanks!