Provide error log message when position cannot be obtained
Co-authored-by: Voyager1 voyager@xbmc.org
Just pushing low hanging fruits we have on our "fork". dvdnav_err_to_string is used whenever DVDNAV_STATUS_ERR is returned but in this particular case the lib doesn't "log" any error message so in the hypothetical case an error happens there we don't know what happened.
