Are you sure you installed 'gcc-multilib'. Otherwise it might be needed to build your own version to avoid these dependency issues.
Now copy the .so in libcod/bin to your library directory or next to your binary.PHP Code:
apt-get install git
git clone https://github.com/kungfooman/libcod.git libcod
cd libcod
./doit.sh base
./doit.sh cod2_1_3
Edit: cod2 is a 32-bit program. But it can run on 64-bit.
@mods it might be better to split the libcod posts to a new thread in the libcod forum.