[CMake][release] Fix config.h.cmake for psurface.

Fix wrong use of #cmakedefine.
(cherry picked from commit 704eb9faeb76192599a205440af28201ec6d5cf5)

Signed-off-by: Christoph Grüninger <gruenich@dune-project.org>
[CMake][bugfix] Fix headercheck for headers below src/.

Reverting conditional CMake traversal of src/ subdirectory introduced
in commit b600783c3e51bbfbf4676f635095328234a964cf.
(cherry picked from commit fbe9a14008931a2f7fca557b2ee89dddd36f0acd)

Signed-off-by: Christoph Grüninger <gruenich@dune-project.org>