Move the SSH-1 servkey and hostkey variables into the coroutine state,

Move the SSH-1 servkey and hostkey variables into the coroutine state,
since there is a theoretical code path (via the crReturn loop after
asking an interactive question about a host key or crypto algorithm)
on which we can leave and return to do_ssh1_login between allocating
and freeing those keys.

(In practice it shouldn't come up anyway with any of the current
implementations of the interactive question functions, not to mention
the unlikelihood of anyone non-specialist still using SSH-1, but
better safe than sorry.)

git-svn-id: http://svn.tartarus.org/sgt/putty@9895 cda61777-01e9-0310-a592-d414129be87e