Extract exception type name from std::exception_ptr on libstdc++

[apolukhin]

There's a public function https://github.com/gcc-mirror/gcc/blob/41d6b10e96a1de98e90a7c0378437c3255814b16/libstdc%2B%2B-v3/libsupc%2B%2B/exception_ptr.h#L153 that returns std::type_info of the exception.

[zajo]

Thank you.