Fixed the printing and charset combo boxes in Unix PuTTY. (The

former by simply removing it; the latter by adding an enumeration
function to libcharset.) This has had slight `const' repercussions
on cp_name() and cp_enumerate() which might break the Mac build.

git-svn-id: svn://svn.tartarus.org/sgt/putty@3064 cda61777-01e9-0310-a592-d414129be87e