updating exp to call the unqualified one, which should be stan::agrad::exp
updating exp to call the unqualified one, which should be stan::agrad::exp

stan-dev/math,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/stan,stan-dev/math,stan-dev/stan