Support getter function name in reexports

[guybedford]

This updates the detection of getter named exports to support named getter functions like:

Object.defineProperty(exports, "a", {
  enumerable: true,
  get: function get() {
    return _asdf.a;
  }
});

where the getter is both the get property and also has a function name since Babel always gives these functions this name in the emit.