The driver currently fails to compile if configure attempts to use libmongoc's bundled version of zlib, since the src/libmongoc/src/zlib-1.2.11/ directory is not added as an include path. Even if the the build were to complete (e.g. it finds zlib.h in some common path) an undefined symbol error would likely result since the driver is neither linked to zlib nor do we compile the bundled version's sources.
This was noticed while compiling the driver with Alpine Linux for PHPC-888.