REGGAE. Black Uhuru - Strongg. (Mesa Records): The music of those dreadlocked Jamaican mystics, the Rastafarians, has changed little since the 1981 death of reggae prophet Bob Marley. Since then, the Kingston-based trio Black Uhuru, like museum curators, have preserved the thumping bass, sultry rhythm, and reggae's revolutionary message - fight European colonialism by rejecting its technology. But the Grammy award-winning band is stuck in a post-prophet funk, offering pleasing but nondescript background music. Some exceptions on their latest release, ``Strongg,'' are the confrontational ``Time Material & Space'' and the plaintive ``I Pray.''