Some code in compat/ has #defines which were not being checked for in configure.ac, which could have lead to compilation failures were those files to be included on systems which needed them. In doing so, we can now remove libmd and libcrypto as these are no longer needed.

Mention that GNU coreutils is no longer required on *BSDs to run the test suite.

Remove libtls/libressl as TLS isn't going to be supported in gotweb any time soon. This reverts commit 5ae325ebc8cde2d9c3810d385f9111597345d597.

Remove dependency on libretls as TLS isn't going to be included in gotwebd any time soon. This reverts commit af7f5027866eea7b4299c2319f83d0eb18a395e6.

Needed for TLS in gotwebd.

This is now required to run gotwebd.

Whenever a CI change is made, also run the test suites. This is enabled for just Ubuntu and FreeBSD for now.

Add Ubuntu as a dedicated CI environment. By default, sh is aliase to dash which often provides interesting challenges for portability, so making this work here is a good thing as mistakes will be spotted earlier.

This needs to be explicitly installed.

Some MacOS systems might not have GNU Bison installed, or have openssl installed. In such instances the host versions of those can be used, with a few tweaks around the edges to make them work. This commit addresses these by: * Relaxing a HAVE_CRYPTO check for __APPLE__, since the inclusion of the machine-specific headers isn't dependent on openssl being installed; * If the non-GNU version of bison on MacOS is being used, define any missing YY* variables, and add a compiler #warning so we log something. This also updates the CI scripts to default to the system versions of bison and removes openssl as a core dependency -- it's more likely openssl is going to be installed, so removing it here will mean we can catch the case for just the MacOS-specific failures, and the inclusion of openssl on other OSes should cover the rest. Noticed by Evan Silberman

Enable CI builds for MaxcOS on CirrusCI.

Cirrus-CI allows for FreeBSD builds as well as Linux.