err_input(): Nailed a small memory leak. If the error is E_INTR, the

err_input(): Nailed a small memory leak.  If the error is E_INTR, the
v temporary variable was never decref'd.  Test this by starting up the
interpreter, hitting C-c, then immediately exiting.

Same potential leak can occur if error is E_NOMEM, since the return is
done in the case block.  Added Py_XDECREF(v); to both blocks, just
before the return.