fix realloc error

src/dump.c

@@ -492,6 +492,7 @@ get_filename_table_size(mrb_state *mrb, mrb_irep *irep, mrb_sym **fp, size_t *lp
     }
     for (i=0; i<irep->rlen; i++) {
       size += get_filename_table_size(mrb, irep->reps[i], fp, lp);
+      filenames = *fp;
     }
   }
   return size;