Not sure if "bug" is the correct category for this issue, but "task" did not seem to convey the same sense or urgency.

59aeacb for mongodb/mongo-c-driver#914 recently introduced #cmakedefine01 preprocessor directives. This is problematic for PHPC, which needs to compile its bundled libmongoc dependency with autotools (to comply with PHP's own build system).

Is it feasible to revert this particular change and/or switch to something more portable that achieves the desired outcome of that PR?