You may have noticed that location of APR/APU documentation changed on APR website (it is now version specific). Although the old links should work, they are actually referring to version 0.9, which may or may not be what APREQ docs should point to (current APREQ were most likely built against 1.2).
Changing APREQ build system to link to APR/APU docs with a specific version number would be the correct thing to do. All this FYI, of course. -- Bojan