shells/zsh links to devel/ncurses

[Alexander Kojevnikov]

If devel/ncurses is installed, shells/zsh links to libncursesw from
that port but doesn't add it as a dependency.

To reproduce:

1. Install devel/ncurses

2. (Re)install shells/zsh

3. Run:
% ldd `shich zsh`
        libncursesw.so.6.0 => /usr/local/lib/libncursesw.so.6.0 (0x8008f4000)
        ...

4. pkg_delete devel/ncurses

5. zsh cannot start:
% ldd `which zsh`
        libncursesw.so.6.0 => not found (0x0)
        ...

Re-building shells/zsh fixes it:

% ldd `which zsh`
        libncursesw.so.8 => /lib/libncursesw.so.8 (0x8008f5000)
        ...

To sum it up, shells/zsh should either not link to devel/ncurses or
list it as a dependency if it does.

Alex