[Libjpeg-devel-6x] Readme build instructions are flawed

[Jonathan W. <jwa...@li...>]

There is a glaring omission from it which anyone who uses *nix will notice right away.

./configure
make
sudo make install

You can never install anything on the Mac without going through the superuser.  I'm fairly certain it's the same way on all *nix distribution.  How this hasn't been fixed yet is beyond me.