Log message:
Add default value for GEM_FORMAT missing from previous commit.

Log message:
Update description to be less rambling and more consise.

Log message:
+ Drop the GEMFILE variable which is completely unused.

+ Add a GEM_SPECFILE variable which points to the gemspec file
  to use when building using the ``gemspec'' GEM_BUILD method.
  It defaults to ${WRKDIR}/${DISTNAME}.gemspec.

+ Add a GEM_FORMAT variable that indicates the archive format of
  the downloaded gem.  Possible are "packed" and "tar" with \ 
a default
  of "tar".  "Packed" is the old gem-0.8.x format, while \ 
"tar" is the
  current one.

+ Make gem-extract a dependency for post-extract, not do-extract.
  This allows for the usual do-extract actions to take place in
  the case where EXTRACT_SUFX is not ".gem".

  Now, if any of the DISTFILES are gems, then gem-extract takes care
  of all of the extraction, but otherwise, the usual do-extract actions
  take place.

+ Use the gem script to unpack the downloaded gem.  We still have to
  manually extract the gemspec file, but at least we make fewer
  assumptions about the format of the gem.

Log message:
Remove PKG_DESTDIR_SUPPORT setting from rubygem.mk.  Its placement in
this file was awkward because PKG_DESTDIR_SUPPORT must be set before
the first inclusion of bsd.prefs.mk, which forced rubygem.mk to be
included before any other file.  Instead, packages which install as
Ruby gems should define PKG_DESTDIR_SUPPORT on their own.

Log message:
+ About half of the gems I've touched have required rubygems>=1.0.1, so
  make that the default version required for dependencies.

+ Same deal for rake>=0.8.1.

Log message:
+ Move the "install into buildroot" step into the build phase and out
  of the install phase.  The whole point of "buildroot" was to avoid
  building anything in the install phase.

Log message:
Extract the gemspec file before the data.tar.gz so that we avoid any
possibility of a name collision with a file named "metadata".

Log message:
Use ${BUILD_TARGET} as the Rakefile task invoked to create the local
gem during the build process.  This allows for specifying non-standard
tasks used by some Ruby packages.  It defaults to "gem".

Log message:
Fix subtle interaction with DESTDIR during installation -- the Makefiles
generated by mkmf.rb are actually not DESTDIR-safe because the $(DESTDIR)
value gets propagated to the rpath.  Since we already pass --buildroot
to deal with staged installations, explicitly strip out DESTDIR from
the environment.

Log message:
Unify the two clauses in _gem-install-cleanbuild that removed the
intermediate build files.  GEM_CLEANBUILD now defaults to "ext/*".