exec/translation-block: Include missing 'qemu/atomic.h' header

exec/translation-block: Include missing 'qemu/atomic.h' header

When moving tb_cflags() in commit 88d4b5138a8 ("tcg: Make
tb_cflags() usable from target-agnostic code") we forgot to
include "qemu/atomic.h", which declares qatomic_read().
Explicitly include it now to avoid issue when refactoring
unrelated headers.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20241217141326.98947-2-philmd@linaro.org>