This reverts commit 9afb2e992136db3fae9a669c3faaf6d5d27602a8.
Conflicts:
* include/CMakeLists.txt
* "Make config.h available" comment: there has been a change
adjacent to where it was removed. Just re-add what was removed.
* tests/CMakeLists.txt:
* compat.sh: there has been a change immediately before where it was
removed. Just re-add what was removed.