Use g_mkdir() to create a directory on all platforms.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Message-Id: <20220927110632.1973965-27-bmeng.cn@gmail.com>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>