How to tell where a symbol is satisfied from.

I have a little test program test.c, and test.o shows '__moddi3' as
an external (thats two underscores at the beginning if they 
dont show in your mail reader).

I have run the script
    for i in lib*
    do
        echo $i
        nm $i | grep __moddi3
    done

over all the lib files in /lib, /usr/lib, and /usr/local/lib, and I dont find 
this
function __moddi3 defined anywhere (its used a number of places, and seems
to be an INTERNAL symbol in a few others,- but never external).

How do I find out where this symbol is defined???
I have a 2nd program where it also appears, but DOESNT get loaded, so
I want to be able to specify the appropriate library.

---

For reference, here is the test program:

#define MULMOD(x,y,p) ((int) ((((long long) (x)) * ((long long) (y))) % ((long 
long) (p))))

main()
{
        long long x, y, p;
        int     i;

        x = 2;
        y = 3;
        p = 4;

        i = MULMOD (x, y, p);
}

-- 
                                        Reg.Clemens
                                        reg@xxxxxxx