By Sudipto Ganguly and Ruma Paul DHAKA (Reuters) -Bangladeshis largely stayed away from the polls in a general election on Sunday set to give Prime Minister Sheikh Hasina a fourth straight term, after a vote boycotted by the main opposition party and marred by violence. Rights groups have warned of virtual one-party rule by Hasina’s Awami League in the South Asian country of 170 million people after the boycott by the Bangladesh Nationalist Party (BNP) and some smaller allies. The United States and Western nations, key customers of Bangladesh’s garment industry, have called for a free and fair…