This bug should probably be closed, as it seems to be a product of user confusion about what apxs -q INCLUDEDIR does. That option has historically (and always will, I suspect) output a single directory, showing the location of the apache header files, containing the prototypes for the ap_* functions.
The fact that ap_* functions also reference apr_* and apu_* functions, and thus will need apr's headers present is irrelevant, much in the way that ap_* functions referencing openssl headers, or db4.2 headers shouldn't be something apxs -q INCLUDEDIR cares about. If you want a full list of -I/foo include directives to feed gcc which should fulfil apache's full list of required include search paths, you want "apxs2 -q EXTRA_INCLUDES". If you find that "apxs2 -q EXTRA_INCLUDES" is also incomplete, please let us know and we'll fix it up to DTRT, but as far as I currently know, it should work. ... Adam