Figured it out! The package "uuid-devel" (which is ossp-uuid, and looks fantastically complicated) puts uuid.h in /usr/include. APR's configure script prefers this over uuid/uuid.h (libuuid's header). OSSP's uuid functions are not compatible with what it expects, so it ends up not using anything.

Removing uuid-devel fixes it (gets rid of /usr/include/uuid.h), although I think this is needed for something with Postgres.

-Michael