libgcj fail to build on Mac OSX

[Jeff Sturm]

On Wed, 10 Sep 2003, Andreas Tobler wrote:
> > /Users/bothner/GNU/gcc.head/libjava/gnu/gcj/runtime/natSharedLibLoader.cc:21:19:
> > dlfcn.h: No such file or directory
>
> You need this package installed:
>
> http://www.opendarwin.org/projects/dlcompat/

Surely it'd be better to have an autoconf test for dlfcn.h?  Otherwise
many Darwin users are bound to be surprised as Per was.

Jeff