simplified alternative to Alien::FFI that uses system libffi

 Alien::FFI makes libffi available to other Perl distributions.
 .
 Alt::Alien::FFI::System provides an alternative implementation of Alien::FFI
 that is geared toward system integrators when libffi is provided by the
 operating system. It will NOT attempt to download or install libffi, contrary
 to the original Alien::FFI.
 .
 DEPRECATED: As of version 0.69, FFI::Platypus will use pkg-config and the
 system libffi if it is already installed, and skip the install of Alien::FFI.
 Thus, this module is now redundant. It may be removed from the CPAN and from
 Debian.