license: Update deprecated SPDX tag LGPL-2.0+ to LGPL-2.0-or-later

The 'LGPL-2.0+' license identifier has been deprecated since license
list version 2.0rc2 [1] and replaced by the 'LGPL-2.0-or-later' [2]
tag.

[1] https://spdx.org/licenses/LGPL-2.0+.html
[2] https://spdx.org/licenses/LGPL-2.0-or-later.html

Mechanical patch running:

  $ sed -i -e s/LGPL-2.0+/LGPL-2.0-or-later/ \
    $(git grep -l 'SPDX-License-Identifier: LGPL-2.0+$')

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
diff --git a/gdbstub/user.c b/gdbstub/user.c
index b36033b..0b4bfa9 100644
--- a/gdbstub/user.c
+++ b/gdbstub/user.c
@@ -6,7 +6,7 @@
  * Copyright (c) 2003-2005 Fabrice Bellard
  * Copyright (c) 2022 Linaro Ltd
  *
- * SPDX-License-Identifier: LGPL-2.0+
+ * SPDX-License-Identifier: LGPL-2.0-or-later
  */
 
 #include "qemu/osdep.h"