Rename the handle-type enumeration values.

Mike Edenfield points out that modern versions of the Windows SDK have
decided that 'INPUT' is a sensible name for an OS data structure
(sigh), and provided a patch to add a disambiguating prefix to
winhandl.c's enum values INPUT, OUTPUT and FOREIGN.


git-svn-id: svn://svn.tartarus.org/sgt/putty@10109 cda61777-01e9-0310-a592-d414129be87e