uapi/linux/stddef.h: Add include guards

stable inclusion
from stable-v5.10.156
commit 95ebea5a15e465385bc2d8178d2f18b7cdba9b03
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7MCG1

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=95ebea5a15e465385bc2d8178d2f18b7cdba9b03



--------------------------------

commit 55037ed7 upstream.

Add include guard wrapper define to uapi/linux/stddef.h to prevent macro
redefinition errors when stddef.h is included more than once. This was not
needed before since the only contents already used a redefinition test.

Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Link: https://lore.kernel.org/r/20220329171252.57279-1-tadeusz.struk@linaro.org


Fixes: 50d7bd38 ("stddef: Introduce struct_group() helper macro")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>