One of his fellow inmates, Nelson Mandela, as a black man, received short pants and no socks.Mr. Kathrada, 83, also showed the Obamas the sign listing the different amounts of sugar, coffee, soup and other foods that South Africa???s prison system had apportioned to blacks; mixed-race inmates, who were known as coloreds; Indians; and whites.???In everything there was apartheid,??? he said in an in