(LENOX, Mass.) – On Saturday, August 4, 2012, pianist Yefim Bronfman joins the Boston Symphony Orchestra at Tanglewood under conductor Christoph von Dohnányi at 8:30 p.m. for a program including Brahms’s Piano Concerto No. 2, a prototypically Brahmsian work in its combination of formal mastery and expressive ingenuity, as well as typically monumental in scale…