Sumudu Fernando points out that in the big r9214 destabilisation I

mistakenly rearranged the logic in an if statement in window.c, with
the effect that scroll-wheel events are no longer sent via xterm mouse
tracking. Put it back to the way it was.

git-svn-id: svn://svn.tartarus.org/sgt/putty@9679 cda61777-01e9-0310-a592-d414129be87e