I have been searching for this many times but never found anything that works.
Example: I want to build the port graphics/libprojectm, but without pulseaudio, which is set by default.
How do I build this port without using the interactive dialog to choose this option, or commenting out lines in Makefile?
What doesn't work:
make OPTIONS=""
make WITHOUT_PULSEAUDIO=1
make OPTIONS_UNSET+=PULSEAUDIO
make WITHOUT="PULSEAUDIO"
make OPTIONS_DEFAULT=""