[REG 3.2.2 -> 3.3.0] Can't build Qt4 demos in default directory

1. Have a checkout of Qt's branch 4.8.
2. Create an out-of-source build of this using the following configure switches

   -opensource -confirm-license -nomake tests -nomake examples -nomake demos
   

   The build directory will contain two XML files named "demos" and "examples", both without a suffix.

3. Configure a kit using this Qt build in Creator.
4. Open a demo from the Qt source directory.
   I used demos\declarative\minehunt\minehunt.pro
5. Configure the demo to use the kit from step 3.
   By some magic, Creator will determine that it should be build inside Qt's build directory.
6. Try to build the demo.
   Build will fail because Creator can not create a subdirectory "demos" due to the file of the same name.

Creator should always be able to build a project using default. If it can't build the project, the defaults are wrong.