[Buildsystem] Fixes quoting with spaces inside dune-control (Part I)

With this patch dunecontrol will work even if the path to the module
contains spaces. Unfortunately, the tests for dune modules will still
not work as I could not figure out how to use quoting in the CPP_FLAGS.
[duneproject] Fixed quoting issues for directories with spaces.
[dunecontrol] Removes issues with whitespace in path for CMake toolchain.
[dunecontrol] Now fails when build with spaces in prefix directory.

Treating directories with spaces in autotools is a can of worms.
We now check whether this situation is given and issue an error when
building with autotools.