aio: call aio_notify after setting I/O handlers

In the current code, this is done by qemu_set_fd_handler2, which is
called by qemu_aio_set_fd_handler.  We need to keep the same behavior
even after removing the call to qemu_set_fd_handler2.

Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

aio-posix.c

@@ -89,6 +89,8 @@ void aio_set_fd_handler(AioContext *ctx,
         node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP : 0);
         node->pfd.events |= (io_write ? G_IO_OUT : 0);
     }
+
+    aio_notify(ctx);
 }
 
 void aio_set_event_notifier(AioContext *ctx,

aio-win32.c

@@ -75,6 +75,8 @@ void aio_set_event_notifier(AioContext *ctx,
         node->io_notify = io_notify;
         node->io_flush = io_flush;
     }
+
+    aio_notify(ctx);
 }
 
 bool aio_pending(AioContext *ctx)