Note: do NOT put file paths to static libraries into FOO_LIBS variables
that are passed to bundled externals that are built with --enable-static:
on Mac OS X this will result in .a archives that contain other .a
archives as entries, and trying to link those results in errors like:

ld: warning: ignoring file .../libodfgen-0.0.a, file was built for
archive which is not the architecture being linked (i386)

Change-Id: If2c5a458058e4da76f80b3643e55b489d1edee24