This reverts commit 9afb2e9921.
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.
Add a test case calling ssl_set_hostname twice to test_suite_ssl.
When run in CMake build mode ASan, this catches the current leak,
but will hopefully be fine with the new version.