undefined functions when using custom NIF library

[Stephen Cuzzort]

I'm trying to create a custom NIF library to handle some number crunching,
but I'm having trouble when I load the nif.  I call
erlang:load_nif("./nifmath", 0), which fails - it says enif_get_string is
undefined.  I'm using gcc with Ubuntu 10.4, and have added liberts to the
library list and included the erlang include directory.

Steve