make pytorch wrapper fails - similar to #54 but a different compiler error

[alex-sorin]

../nv_wavenet_util.cuh(89): error: more than one conversion function from "half" to a built-in type applies:
function "__half::operator float() const"
function "__half::operator short() const"
function "__half::operator unsigned short() const"
function "__half::operator int() const"
function "__half::operator unsigned int() const"
function "__half::operator long long() const"
function "__half::operator unsigned long long() const"
function "__half::operator __nv_bool() const"

[chh7411898]

i have the same question