----- Edit -----
Okay, should have just looked in the config.log:
Threads are enabled by default. But my question about pthreads still stands....
configure:9508: checking for --enable-protocol_file
configure:9538: result: yes
configure:9553: checking for --enable-threads
configure:9583: result: yes
configure:9598: checking for --enable-iniconf
configure:9628: result: no
...