Gwamnatin Burundi ta amince da wata ayar doka da za ta bada damar kawo sauyi a kundin tsarin mulkin kasar, wanda kuma hakan zai iya bai wa shugaba Pierre Nkurunziza damar neman wasu wa’adin mulki har biyu na shekaru bakwai-bakwai a nan gaba daga 2020.