The Bronze is a mutant baby of a movie that shouldn’t work as well as it does (though as the X-Men have proven, mutants can be cute, too). In Bryan Buckley’s clunky if affecting debut, the jerk-com melds with the rom-com in the tiny blonde form of Hope Ann Greggory (four-feet-eleven cowriter Melissa Rauch), a former Olympic gymnast whose post-athletic existence is so empty that she spanks it to a video of her 2004 bronze-winning routine…