Pavel Wonka, a leading Czech human rights activist, has died in prison, an emigre source said. Wonka, 35, died Tuesday, five days after he was sentenced to a second prison term of five months, said the source, who spoke on condition of anonymity. Both he and and the Prague-based Committee for the Unjustly Persecuted have reported that Wonka and his brother Jiri were repeatedly beaten in prison. Wonka had been released Feb. 26 after serving a 21-month prison sentence. He was convicted in May, 1986, of "incitement to rebellion" and "insulting police in execution of their official duties."