The gcc version requires that; the icc version does not.
Or at least, ldd thinks that the icc version that I'm running right now is trying to link in libncurses.so.5. Having just grabbed the gcc version as well, I can see that ldd thinks that it's trying to link in libncurses.so.4 instead.
No, I'm not sure why this is... unless it has something to do with the fact that they compiled the gcc version on a Red Hat 6.2 machine?