We could run the Jansson tests for the JSON code ...
Ha! Wrong comment for this issue. But it's still resolved as WONTFIX; I haven't heard any clamoring for us to run the Jansson tests.
We can recreate a config.h file if we add any features that require it.
The autotools builds did this, but I find them to be overkill; let the Jansson project run the Jansson tests. We're only placing well-tested stable releases into our code tree anyway. Our testing framework can focus on testing our code.