Fix FTBFS with clang

This resolves bug 2894

Signed-off-by: Ray Vine <ray-v@inbox.lv>
(cherry picked from commit 239c8a48ec)

src/kile/kileprojectview.h

@@ -25,7 +25,9 @@
 class KURL;
 class TDEPopupMenu;
 class TDEToggleAction;
-class KileDocument::Info;
+namespace KileDocument {
+    class Info;
+}
 class KileInfo;
 
 namespace KileType {enum ProjectView { Project=0, ProjectItem, ProjectExtra, File, Folder};}