Log Message:
* Remove unnecessary dependency on guile.  The guile wrappers are currently
  _never_ built, regardless of whether guile is detected or not.
* Strongly buildlinkify.
* Use LIBTOOL_OVERRIDE instead of LTCONFIG_OVERRIDE so that the correct
  libtool is used during the build and installation.
* Add a pre-build target to symlink the libxml headers into ${WRKSRC} so
  that references to <libxml/foo.h> will resolve to <gnome-xml/foo.h>.  I
  imagine that the sources will be fixed to refer to more recent header
  locations in a future release of GConf.