Further fallout from the introduction of the Filename type. (Memo to

self: if you change the type of a variable and everything compiles
without type-checking errors, that doesn't mean it's all fixed,
because variadic functions aren't type-checked! Oops.)

git-svn-id: svn://svn.tartarus.org/sgt/putty@2799 cda61777-01e9-0310-a592-d414129be87e