linbox: backport upstream fixes
References:
https://github.com/linbox-team/linbox/commit/f78117d9c365efd46f5ea2903b553a08c4029aeb
https://github.com/linbox-team/linbox/commit/4ff828e20053ab2ef9adc4ce6931d159fd513cef
Signed-off-by: Masanori Ogino <167209+omasanori@users.noreply.github.com>