RequestUtil: Slightly better error message if not running on 64-bit PHP.
RequestUtil: Slightly better error message if not running on 64-bit PHP.

dropbox/dropbox-sdk-php,demisang/dropbox-sdk-php,sayfulit/dropbox-sdk-php,TimeDoctorLLC/dropbox-sdk-php,itsazzad/dropbox-sdk-php,sayfulit/dropbox-sdk-php,itsazzad/dropbox-sdk-php,dropbox/dropbox-sdk-php,TimeDoctorLLC/dropbox-sdk-php,demisang/dropbox-sdk-php