Try to fix building on OSX (and I assume WIN32) following
some changes introduced in r10248 that were causing issues
with including X11.h on non-X11 platforms.



git-svn-id: http://seriss.com/public/fltk/fltk/branches/branch-1.3@10254 ea41ed52-d2ee-0310-a9c1-e6b18d33e121