Arguably no major gay-themed film has ever been as polarizing within the queer community as 1980’s  Cruising , the gritty William Friedkin crime thriller set against the backdrop of New York’s leather-bar scene. Documentarian Jeffrey Schwarz takes a three-pronged approach to the subject in  Mineshaft: The Cruising Murders , examining the real-life homicide that inspired the story, the development and filming on New York locations, and the controversies that dogged the shoot, with massive protest crowds of LGBTQ rights activists disrupting production and rattling the star, Al Pacino .…