The port devel/apr does not enable threads as advertised. There is a knob to *disable* threads, but the default build on this release does not properly enable threads.
Add --enable-threads to Makefile CONFIGURE_ARGS in default case.
How-To-Repeat: Build and install /usr/ports/devel/apr.
Observe configure output indicating threads are not enabled.
Look in /usr/local/include/apr-1/apr.h for APR_HAS_THREADS and observe it is set to 0.
Awaiting maintainers feedback