When clarinetist Anthony McGill visits Ravinia on July 15 to perform the Brahms Clarinet Quintet with the Takács String Quartet, the occasion will be the latest of numerous homecomings the Chicago native has enjoyed since he left the nest for the Interlochen Music Academy and the Curtis Institute of Music many years ago. Originally from the Chatham neighborhood on the city’s South Side, McGill and his unlikely rise to the summit of the clarinet world was fueled by a supreme talent, supportive family, several key local mentors, and an unflagging determination.