MDEV-29443: prevent uring access to galera sst /notify scripts

The resources like uring in MariaDB aren't intended for spawned
processes so we restrict access using the io_uring_ring_dontfork
liburing library call.

tpool/aio_liburing.cc

@@ -63,6 +63,12 @@ class aio_uring final : public tpool::aio
  }
  throw std::runtime_error("aio_uring()");
  }
+ if (io_uring_ring_dontfork(&uring_) != 0)
+ {
+ my_printf_error(ER_UNKNOWN_ERROR,
+ "io_uring_dontfork() failed with errno %d (continuing)",
+ ME_ERROR_LOG | ME_WARNING, errno);
+ }
 
  thread_= std::thread(thread_routine, this);
  }