modules: Fix building with --enable-modules

Compiling util/modules.c with modules enabled fails now.

Fix it by including qemu-common.h before #ifdef testing in module.c.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 1393453893-12125-1-git-send-email-famz@redhat.com
Reviewed-by: Hu Tao <hutao@cn.fujitsu.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>