Log Message:
devel/ruby-ffi-compiler: fix runtime problem

Install loadable modules into GEM_EXTSDIR.

On some platform, ruby-ffi/ruby-ffi-compiler defines their own OS/ARCH name
and it cause using diffrernt directory to install loadable modules.

In this case (NetBSD/i386), installed loadable modules never loaded
successfully since they exists on a directory which dose not contained in
Ruby's global variable "$:".

Focus to PR pkg/55469.

Bump PKGREVISION.