I found just 2 other aout directories to look at:
find . -type f -name PLIST -exec grep -l aout {} \;
	databases/interbase4/pkg/PLIST
		lib/aout/libgds.a
		lib/aout/libgds_pyxis.a
		lib/aout/libgdsflib.so.0.0 
		lib/aout/libgdslib.so.0.1
		lib/aout/libgdslib.so.1.0
		lib/aout/libgdsintl.so
		lib/aout/libgdslib.so
	www/libxpg4-ns/pkg/PLIST
		lib/aout/libxpg4-ns.a
		lib/aout/libxpg4-ns.so.2.0
		lib/aout/libxpg4-ns_p.a  
		@exec env OBJFORMAT=aout ldconfig -m %B
		@unexec env OBJFORMAT=aout ldconfig -R %B