I'm getting an error compiling ruby 1.8.4 on a mac book pro.

After running configure as follows:

./configure --prefix=/usr/local --with-readline-dir=/usr/local 
--enable-shared --enable-pthread

make stops with this error:

gcc main.o  libruby-static.a -lpthread -ldl -lobjc   -o miniruby -g 
-O2  -fno-common -pipe -fno-common  -DRUBY_EXPORT
/usr/bin/ld: Undefined symbols:
_Init_ext
collect2: ld returned 1 exit status
make: *** [miniruby] Error 1

Any ideas?

Thanks
-- 
- Stephen Bannasch
   Concord Consortium, http://www.concord.org